AoC 2019 Day9 FORTRAN

PROGRAM DAY9
  USE MPI

  INTEGER :: I,IERR,A,B,C,D,E,N
  INTEGER(8) :: PART1,PART2
  CHARACTER(LEN=1) CHAR
  INTEGER, ALLOCATABLE :: PROG(:)
  INTEGER :: IERROR, NPROC, ICOMM, IRANK ,INTERCOMM ,ERRCODES(1)
  LOGICAL :: AMROOT,RUNNING,SETUP,FIRST
  INTEGER :: STATUS(MPI_STATUS_SIZE)

  CALL MPI_INIT(IERROR)
  ICOMM = MPI_COMM_WORLD
  CALL MPI_COMM_SIZE(ICOMM,NPROC,IERROR)
  CALL MPI_COMM_RANK(ICOMM, IRANK, IERROR)
  CALL MPI_COMM_SPAWN("./intcode",MPI_ARGV_NULL,1,MPI_INFO_NULL,0,ICOMM,INTERCOMM,ERRCODES,IERROR)

  OPEN(1,FILE="input.txt")
  N=1
  DO
     READ(1,'(A1)',IOSTAT=IERR,ADVANCE="NO")CHAR
     IF(IERR.NE.0)EXIT
     IF(CHAR.EQ.",")N=N+1
  END DO
  REWIND(1)
  ALLOCATE(PROG(0:N-1))
  READ(1,*)PROG


  CALL MPI_SEND(N,1,MPI_INTEGER,I,0,INTERCOMM,IERROR)
  CALL MPI_SEND(PROG,N,MPI_INTEGER,I,1,INTERCOMM,IERROR)


  CALL MPI_SEND(1_8,1,MPI_DOUBLE_PRECISION,0,2,INTERCOMM,IERROR)
  CALL MPI_RECV(PART1,1,MPI_DOUBLE_PRECISION,0,999,INTERCOMM,STATUS,IERROR)
  WRITE(*,'("Part 1: ",I0)') PART1
  CALL MPI_SEND(2_8,1,MPI_DOUBLE_PRECISION,0,2,INTERCOMM,IERROR)
  CALL MPI_RECV(PART2,1,MPI_DOUBLE_PRECISION,0,999,INTERCOMM,STATUS,IERROR)
  WRITE(*,'("Part 2: ",I0)') PART2
  CALL MPI_SEND(-1_8,1,MPI_DOUBLE_PRECISION,0,2,INTERCOMM,IERROR)
  CALL MPI_FINALIZE(IERROR)

END PROGRAM DAY9