MPI_Recv (buf0, buf_size, MPI_INT, drank, 0, intercomm, &status);
MPI_Send (buf1, buf_size, MPI_INT, drank, 0, intercomm);
}
else {
MPI_Recv (buf0, buf_size, MPI_INT, drank, 0, intercomm, &status);
MPI_Send (buf1, buf_size, MPI_INT, drank, 0, intercomm);
}
else {