program ch2801
use mpi
implicit none
integer :: error_number
integer :: this_process_number
integer :: number_of_processes

  call mpi_init(error_number)
  call mpi_comm_size(mpi_comm_world,number_of_processes,error_number)
  call mpi_comm_rank(mpi_comm_world,this_process_number,error_number)
  print *, ' Hello from process ', this_process_number, ' of ', &
    number_of_processes, 'processes!'
  call mpi_finalize(error_number)
end program ch2801