#include <stdio.h>
#include <mpi.h>
#define N 10

void main(int argc, char **argv )
 {
  int *a, *b;
  int i;
  int myid, numprocs;
  int myfirst;
  MPI_Status status;

  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &myid); 

  a = (int *) malloc (N * sizeof(int));
  myfirst = myid*N;
  for (i=0;i<N;i++) { a[i] = myfirst+i; } 

  if (myid == 0) b=(int *) malloc(numprocs * N * sizeof(int));
  MPI_Gather(a,N,MPI_INT,b,N,MPI_INT,0,MPI_COMM_WORLD);

  if (myid == 0) 
    for (i=0;i<(N*numprocs);i++)
     if (b[i]) printf("%d\t%d\n",i,b[i]); 
  MPI_Finalize();
 }