AoC 2019 Day1 FORTRAN

PROGRAM DAY1
  INTEGER :: I,N,IERR,FUEL,TOTALFUEL
  INTEGER, ALLOCATABLE :: MASSES(:)

  ! Input
  OPEN(1,FILE="INPUT.TXT")
  N=0
  DO
     READ(1,*,IOSTAT=IERR) I
     IF(IERR.NE.0)EXIT
     N=N+1
  END DO
  REWIND(1)
  ALLOCATE(MASSES(N))
  READ(1,*) MASSES
  CLOSE(1)

  ! Part 1
  WRITE(*,'(A,I0)') "Part 1: ",SUM(MASSES/3-2)

  ! Part 2
  TOTALFUEL=0
  DO I=1,N
     FUEL = MASSES(I)/3-2
     DO
        IF(FUEL<=0)EXIT
        TOTALFUEL=TOTALFUEL+FUEL
        FUEL=FUEL/3-2
     END DO
  END DO
  WRITE(*,'(A,I0)') "Part 2: ",TOTALFUEL

END PROGRAM DAY1