IF ( exch2_pj(1,4,n1).eq.-1 ) THEN

         IF ( exch2_pj(2,4,n1).eq.1 ) THEN

       exch2_pj(1,1,12)=0

       exch2_pj(2,1,12)=1

       exch2_pj(1,2,12)=0

       exch2_pj(2,2,12)=1

       exch2_pj(1,3,12)=-1

       exch2_pj(2,3,12)=0

       exch2_pj(1,4,12)=0

       exch2_pj(2,4,12)=1

       exch2_pj(1,1,2)=1

       exch2_pj(2,1,2)=0

       exch2_pj(1,2,2)=1

       exch2_pj(2,2,2)=0

       exch2_pj(1,3,2)=0

       exch2_pj(2,3,2)=1

       exch2_pj(1,4,2)=0

       exch2_pj(2,4,2)=1

       exch2_pj(1,5,2)=-1

       exch2_pj(2,5,2)=0

       exch2_pj(1,1,3)=0

       exch2_pj(2,1,3)=1

       exch2_pj(1,2,3)=1

       exch2_pj(2,2,3)=0

       exch2_pj(1,3,3)=1

       exch2_pj(2,3,3)=0

       exch2_pj(1,4,3)=-1

       exch2_pj(2,4,3)=0

       exch2_pj(1,5,3)=0

       exch2_pj(2,5,3)=1

       exch2_pj(1,1,4)=0

       exch2_pj(2,1,4)=1

       exch2_pj(1,2,4)=0

       exch2_pj(2,2,4)=1

       exch2_pj(1,3,4)=-1

       exch2_pj(2,3,4)=0

       exch2_pj(1,4,4)=0

       exch2_pj(2,4,4)=1

       exch2_pj(1,1,5)=0

       exch2_pj(2,1,5)=1

       exch2_pj(1,2,5)=0

       exch2_pj(2,2,5)=1

       exch2_pj(1,3,5)=0

       exch2_pj(2,3,5)=1

       exch2_pj(1,1,1)=0

       exch2_pj(1,4,5)=-1

       exch2_pj(2,4,5)=0

       exch2_pj(2,1,1)=1

       exch2_pj(1,1,6)=1

       exch2_pj(2,1,6)=0

       exch2_pj(1,2,6)=1

       exch2_pj(2,2,6)=0

       exch2_pj(1,3,6)=0

       exch2_pj(2,3,6)=1

       exch2_pj(1,4,6)=0

       exch2_pj(2,4,6)=1

       exch2_pj(1,5,6)=-1

       exch2_pj(2,5,6)=0

       exch2_pj(1,1,7)=0

       exch2_pj(2,1,7)=1

       exch2_pj(1,2,1)=0

       exch2_pj(1,2,7)=1

       exch2_pj(2,2,7)=0

       exch2_pj(2,2,1)=1

       exch2_pj(1,3,7)=1

       exch2_pj(2,3,7)=0

       exch2_pj(1,4,7)=-1

       exch2_pj(2,4,7)=0

       exch2_pj(1,5,7)=0

       exch2_pj(2,5,7)=1

       exch2_pj(1,1,8)=0

       exch2_pj(2,1,8)=1

       exch2_pj(1,2,8)=0

       exch2_pj(2,2,8)=1

       exch2_pj(1,3,8)=-1

       exch2_pj(2,3,8)=0

       exch2_pj(1,4,8)=0

       exch2_pj(2,4,8)=1

       exch2_pj(1,3,1)=0

       exch2_pj(2,3,1)=1

       exch2_pj(1,1,9)=0

       exch2_pj(2,1,9)=1

       exch2_pj(1,2,9)=0

       exch2_pj(2,2,9)=1

       exch2_pj(1,3,9)=0

       exch2_pj(2,3,9)=1

       exch2_pj(1,4,9)=-1

       exch2_pj(2,4,9)=0

       exch2_pj(1,1,10)=1

       exch2_pj(2,1,10)=0

       exch2_pj(1,2,10)=1

       exch2_pj(2,2,10)=0

       exch2_pj(1,3,10)=0

       exch2_pj(2,3,10)=1

       exch2_pj(1,4,10)=0

       exch2_pj(2,4,10)=1

       exch2_pj(1,4,1)=-1

       exch2_pj(1,5,10)=-1

       exch2_pj(2,5,10)=0

       exch2_pj(2,4,1)=0

       exch2_pj(1,1,11)=0

       exch2_pj(2,1,11)=1

       exch2_pj(1,2,11)=1

       exch2_pj(2,2,11)=0

       exch2_pj(1,3,11)=1

       exch2_pj(2,3,11)=0

       exch2_pj(1,4,11)=-1

       exch2_pj(2,4,11)=0

       exch2_pj(1,5,11)=0

       exch2_pj(2,5,11)=1

       INTEGER exch2_pj(2,MAX_NEIGHBOURS,NTILES)

     &        exch2_pi,exch2_pj,                  

       exch2_pj(1,1,127)=0

       exch2_pj(2,1,127)=1

       exch2_pj(1,2,127)=0

       exch2_pj(2,2,127)=1

       exch2_pj(1,3,127)=0

       exch2_pj(2,3,127)=1

       exch2_pj(1,1,128)=0

       exch2_pj(2,1,128)=1

       exch2_pj(1,2,11)=0

       exch2_pj(2,2,11)=1

       exch2_pj(1,2,128)=0

       exch2_pj(2,2,128)=1

       exch2_pj(1,3,128)=0

       exch2_pj(2,3,128)=1

       exch2_pj(1,4,128)=0

       exch2_pj(2,4,128)=1

       exch2_pj(1,1,129)=0

       exch2_pj(2,1,129)=1

       exch2_pj(1,2,129)=0

       exch2_pj(2,2,129)=1

       exch2_pj(1,3,129)=0

       exch2_pj(2,3,129)=1

       exch2_pj(1,4,129)=0

       exch2_pj(2,4,129)=1

       exch2_pj(1,3,11)=0

       exch2_pj(1,1,130)=0

       exch2_pj(2,1,130)=1

       exch2_pj(2,3,11)=1

       exch2_pj(1,2,130)=0

       exch2_pj(2,2,130)=1

       exch2_pj(1,3,130)=0

       exch2_pj(2,3,130)=1

       exch2_pj(1,4,130)=0

       exch2_pj(2,4,130)=1

       exch2_pj(1,1,131)=0

       exch2_pj(2,1,131)=1

       exch2_pj(1,2,131)=0

       exch2_pj(2,2,131)=1

       exch2_pj(1,3,131)=0

       exch2_pj(2,3,131)=1

       exch2_pj(1,4,131)=-1

       exch2_pj(2,4,131)=0

       exch2_pj(1,4,11)=0

       exch2_pj(2,4,11)=1

       exch2_pj(1,1,132)=0

       exch2_pj(2,1,132)=1

       exch2_pj(1,2,132)=0

       exch2_pj(2,2,132)=1

       exch2_pj(1,3,132)=0

       exch2_pj(2,3,132)=1

       exch2_pj(1,4,132)=0

       exch2_pj(2,4,132)=1

       exch2_pj(1,1,133)=0

       exch2_pj(2,1,133)=1

       exch2_pj(1,2,133)=0

       exch2_pj(2,2,133)=1

       exch2_pj(1,3,133)=0

       exch2_pj(2,3,133)=1

       exch2_pj(1,4,133)=0

       exch2_pj(2,4,133)=1

       exch2_pj(1,1,134)=0

       exch2_pj(2,1,134)=1

       exch2_pj(1,2,134)=0

       exch2_pj(2,2,134)=1

       exch2_pj(1,3,134)=0

       exch2_pj(2,3,134)=1

       exch2_pj(1,4,134)=0

       exch2_pj(2,4,134)=1

       exch2_pj(1,1,135)=0

       exch2_pj(2,1,135)=1

       exch2_pj(1,2,135)=0

       exch2_pj(2,2,135)=1

       exch2_pj(1,3,135)=0

       exch2_pj(2,3,135)=1

       exch2_pj(1,4,135)=-1

       exch2_pj(2,4,135)=0

       exch2_pj(1,1,136)=0

       exch2_pj(2,1,136)=1

       exch2_pj(1,1,12)=0

       exch2_pj(1,2,136)=0

       exch2_pj(2,2,136)=1

       exch2_pj(2,1,12)=1

       exch2_pj(1,3,136)=0

       exch2_pj(2,3,136)=1

       exch2_pj(1,4,136)=0

       exch2_pj(2,4,136)=1

       exch2_pj(1,1,137)=0

       exch2_pj(2,1,137)=1

       exch2_pj(1,2,137)=0

       exch2_pj(2,2,137)=1

       exch2_pj(1,3,137)=0

       exch2_pj(2,3,137)=1

       exch2_pj(1,1,138)=0

       exch2_pj(2,1,138)=1

       exch2_pj(1,2,138)=0

       exch2_pj(2,2,138)=1

       exch2_pj(1,2,12)=0

       exch2_pj(2,2,12)=1

       exch2_pj(1,3,138)=0

       exch2_pj(2,3,138)=1

       exch2_pj(1,4,138)=0

       exch2_pj(2,4,138)=1

       exch2_pj(1,1,139)=0

       exch2_pj(2,1,139)=1

       exch2_pj(1,2,139)=0

       exch2_pj(2,2,139)=1

       exch2_pj(1,3,139)=0

       exch2_pj(2,3,139)=1

       exch2_pj(1,4,139)=-1

       exch2_pj(2,4,139)=0

       exch2_pj(1,1,140)=0

       exch2_pj(2,1,140)=1

       exch2_pj(1,3,12)=0

       exch2_pj(1,2,140)=0

       exch2_pj(2,2,140)=1

       exch2_pj(2,3,12)=1

       exch2_pj(1,3,140)=0

       exch2_pj(2,3,140)=1

       exch2_pj(1,1,141)=0

       exch2_pj(2,1,141)=1

       exch2_pj(1,2,141)=0

       exch2_pj(2,2,141)=1

       exch2_pj(1,3,141)=0

       exch2_pj(2,3,141)=1

       exch2_pj(1,1,142)=1

       exch2_pj(2,1,142)=0

       exch2_pj(1,2,142)=1

       exch2_pj(2,2,142)=0

       exch2_pj(1,4,12)=0

       exch2_pj(1,3,142)=0

       exch2_pj(2,3,142)=1

       exch2_pj(2,4,12)=1

       exch2_pj(1,4,142)=0

       exch2_pj(2,4,142)=1

       exch2_pj(1,5,142)=-1

       exch2_pj(2,5,142)=0

       exch2_pj(1,1,143)=1

       exch2_pj(2,1,143)=0

       exch2_pj(1,2,143)=1

       exch2_pj(2,2,143)=0

       exch2_pj(1,3,143)=0

       exch2_pj(2,3,143)=1

       exch2_pj(1,4,143)=0

       exch2_pj(2,4,143)=1

       exch2_pj(1,1,144)=1

       exch2_pj(2,1,144)=0

       exch2_pj(1,2,144)=1

       exch2_pj(2,2,144)=0

       exch2_pj(1,3,144)=0

       exch2_pj(2,3,144)=1

       exch2_pj(1,4,144)=0

       exch2_pj(2,4,144)=1

       exch2_pj(1,1,145)=0

       exch2_pj(2,1,145)=1

       exch2_pj(1,2,145)=1

       exch2_pj(2,2,145)=0

       exch2_pj(1,3,145)=1

       exch2_pj(2,3,145)=0

       exch2_pj(1,4,145)=0

       exch2_pj(2,4,145)=1

       exch2_pj(1,5,145)=0

       exch2_pj(2,5,145)=1

       exch2_pj(1,1,146)=0

       exch2_pj(2,1,146)=1

       exch2_pj(1,2,146)=1

       exch2_pj(2,2,146)=0

       exch2_pj(1,1,13)=0

       exch2_pj(1,3,146)=1

       exch2_pj(2,3,146)=0

       exch2_pj(2,1,13)=1

       exch2_pj(1,4,146)=0

       exch2_pj(2,4,146)=1

       exch2_pj(1,5,146)=0

       exch2_pj(2,5,146)=1

       exch2_pj(1,1,147)=0

       exch2_pj(2,1,147)=1

       exch2_pj(1,2,147)=1

       exch2_pj(2,2,147)=0

       exch2_pj(1,3,147)=1

       exch2_pj(2,3,147)=0

       exch2_pj(1,4,147)=0

       exch2_pj(2,4,147)=1

       exch2_pj(1,5,147)=0

       exch2_pj(2,5,147)=1

       exch2_pj(1,2,13)=0

       exch2_pj(2,2,13)=1

       exch2_pj(1,1,148)=0

       exch2_pj(2,1,148)=1

       exch2_pj(1,2,148)=1

       exch2_pj(2,2,148)=0

       exch2_pj(1,3,148)=1

       exch2_pj(2,3,148)=0

       exch2_pj(1,4,148)=-1

       exch2_pj(2,4,148)=0

       exch2_pj(1,5,148)=0

       exch2_pj(2,5,148)=1

       exch2_pj(1,1,149)=0

       exch2_pj(2,1,149)=1

       exch2_pj(1,2,149)=0

       exch2_pj(2,2,149)=1

       exch2_pj(1,3,149)=0

       exch2_pj(2,3,149)=1

       exch2_pj(1,3,13)=0

       exch2_pj(1,4,149)=0

       exch2_pj(2,4,149)=1

       exch2_pj(2,3,13)=1

       exch2_pj(1,1,150)=0

       exch2_pj(2,1,150)=1

       exch2_pj(1,2,150)=0

       exch2_pj(2,2,150)=1