Include 'mpif.h'
        integer numtasks, rank, next, prev, buf(2), tag1, tag2, ierr 
       integer stats(MPI_STATUS_SIZE,4), reqs(4) 
       tag1 = 1 
       tag2 = 2 
       call MPI_INIT(ierr) 
       callMPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr) 
       callMPI_COMM_SIZE(MPI_COMM_WORLD, numtasks, ierr) 
       prev = rank - 1 
       next = rank + 1 
       if (rank .eq. 0) then 
       prev = numtasks - 1 
       endif 
       if (rank .eq. numtasks - 1) then 
       next = 0 
       endif 

       call MPI_IRECV(buf(1), 1, MPI_INTEGER, prev, tag1,  
     & MPI_COMM_WORLD, reqs(1), ierr) 
       call MPI_IRECV(buf(2), 1, MPI_INTEGER, next, tag2,  
     & MPI_COMM_WORLD, reqs(2), ierr) 
       call MPI_ISEND(rank, 1, MPI_INTEGER, prev, tag2, 
     & MPI_COMM_WORLD, reqs(3), ierr) 
       call MPI_ISEND(rank, 1, MPI_INTEGER, next, tag1, 
     & MPI_COMM_WORLD, reqs(4), ierr) 

       call MPI_WAITALL(4,reqs, stats, ierr); 
       call MPI_FINALIZE(ierr) 
       end