#include <stdio.h>
#include <mpi.h>
#include <unistd.h>
#define HOST_NAME_MAX 127

int main (int argc, char *argv[])
{
        int rank, size;
        char hname[HOST_NAME_MAX+1];

        MPI_Init(&argc, &argv);
        MPI_Comm_rank(MPI_COMM_WORLD, &rank);
        MPI_Comm_size(MPI_COMM_WORLD, &size);

        gethostname(hname, HOST_NAME_MAX);
        printf("Hello World! from Process %d of %d on %s\n", rank,size,hname);

        MPI_Finalize();
}