#include <mpi.h>
#include <iostream>
using namespace std;

int main(int argc, char **argv)
{
    MPI_Init(&argc, &argv);

    int rank, size;

    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    if( rank )
    {
        char buf[] = "Hello!";
        MPI_Send(buf, sizeof(buf), MPI_CHAR, 0, 0, MPI_COMM_WORLD);
    } else {
        cout << "Process 0 started" << endl;
        for(int i(1); i<size; ++i)
        {
            MPI_Status s;
            MPI_Probe(MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &s);
            int count;
            MPI_Get_count(&s, MPI_CHAR, &count);

            char *buf = new char[count];
            MPI_Recv(buf, count, MPI_CHAR,
                     MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &s);
            cout << "Message from process " << s.MPI_SOURCE << ": "
                 << buf << endl;
            delete[] buf;
        }
        cout << "Done." << endl;
    }

    MPI_Finalize();
    return 0;
}