program main

      include 'mpif.h'

      integer error
      integer my_id
      integer num_procs

      call MPI_Init ( error )

      call MPI_Comm_rank ( MPI_COMM_WORLD, my_id, error )

      if ( my_id == 0 ) then
        call MPI_Comm_size ( MPI_COMM_WORLD, num_procs, error )
        print, ' '
        print, 'HELLO_WORLD - Master process:'
        print, '  A FORTRAN77 program using MPI.'
        print, ' '
        print, '  The number of processes is ', num_procs
        print, ' '
      else
        print, ' '
        print, '  Process ', my_id, ' says "Hello, world!"'
      end if

      call MPI_Finalize ( error )

      stop
      end