recv_count * num_procs_completed,
recv_type, dst, tag, comm, &status);
// num_procs_completed is also equal to the no. of processes
// whose data we don't have
recv_count * num_procs_completed,
recv_type, dst, tag, comm, &status);
// num_procs_completed is also equal to the no. of processes
// whose data we don't have