MPI_COMM_SIZE(comm, size) [ IN comm] communicator (handle) [ OUT size] number of processes in the group of comm (integer) Code int MPI_Comm_size(MPI_Comm comm, int *size)This call returns the number of process involved in a communicator. When the communicator used is the predefined global communicator
MPI_COMM_WORLD, then this function indicates the total number
of processes involved in the program.