#include <mpi.h> 
#include <stdio.h>
int main(int argc, char *argv[]) {  
    int commsize, my_rank;

    MPI_Init(&argc, &argv);  
    
    MPI_Comm_size(MPI_COMM_WORLD, &commsize);
    MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
    printf ("Communicator size = %d; My rank = %d\n", commsize,my_rank);  
    
    MPI_Finalize();
}