program main

!-- All processes send a message to process 0

      implicit none

!--Include the mpi header file
      include 'mpif.h'
      integer i,ierr,myid,numprocs,itag
      integer message,mess_received,iroot_pe,itag,icount,ierror
      integer status(MPI_STATUS_SIZE)
      integer irc

!--Initialize MPI
      call MPI_INIT( ierr )

!--Who am I? --- get my rank=myid
      call MPI_COMM_RANK( MPI_COMM_WORLD, myid, ierr )

!--How many processes in the global group?
      call MPI_COMM_SIZE( MPI_COMM_WORLD, numprocs, ierr )
      print *, "Process ", myid, " of ", numprocs, " is alive"

!--Compose the message
      message=myid

!--Send a message to process 0
        icount=1
        iroot_pe=0
      if(myid /= 0) then
        itag=myid
        call mpi_send(message,icount,MPI_INTEGER,iroot_pe,itag,
     &   MPI_COMM_WORLD,ierror)
      else
        do i=1,numprocs-1
         itag=i
         call mpi_recv(mess_received,icount,MPI_INTEGER,i,
     &     itag,MPI_COMM_WORLD,
     &     status,ierror)
         print *,'received message from process',mess_received
        end do
      end if

!--Finilize MPI
      call MPI_FINALIZE(irc)

      stop
      end