#include <stdio.h> 
#include "mpi.h" 
int main(int argc, char **argv) 
{
    int size;

    MPI_Init(&argc, &argv); 
    MPI_Comm_size(MPI_COMM_WORLD, &size); 
    printf("size %d\n", size);
    MPI_Finalize();

    return 0;
}