#include <stdio.h>
#include <mpi.h>


int main (int argc, char *argv[])
{
  MPI_Status stat;
  int me, np, tag=313;
  double value;
  MPI_Init (&argc, &argv);/* starts MPI */
  MPI_Comm_rank (MPI_COMM_WORLD, &me);/* get current process id */
  MPI_Comm_size (MPI_COMM_WORLD, &np);/* get number of processes */
  if ( me==0 ) {
    value = 0.125;
    if ( np > 1 )
      MPI_Send( &value, 1, MPI_DOUBLE, 1, tag, MPI_COMM_WORLD );
    else
      printf("Master is the only task. Value=%lf\n",value);
  } else {
    if ( me == np-1 ) {
      MPI_Recv( &value, 1, MPI_DOUBLE, me-1, tag, MPI_COMM_WORLD, &stat );
      printf("Task #%d is the last one. Value=%lf\n",me,value);
    } else {
      MPI_Recv( &value, 1, MPI_DOUBLE, me-1, tag, MPI_COMM_WORLD, &stat );
      MPI_Send( &value, 1, MPI_DOUBLE, me+1, tag, MPI_COMM_WORLD );
    }
  }
  MPI_Finalize();
  return 0;
}