First AoC problem in Fortran

aoc1.f77

      PROGRAM AOC1                                                      000010AA
      IMPLICIT NONE                                                     000020AA
C     --------DECLARATIONS--------------------------------------------- 000030AA
      CHARACTER :: C                                                    000040AA
      INTEGER :: STATUS, FLOOR, STEP                                    000050AA
      LOGICAL :: BASEMENT                                               000060AA
C     --------STATEMENTS----------------------------------------------- 000070AA
      BASEMENT = .FALSE.                                                000080AA
      FLOOR = 0                                                         000090AA
      STEP = 0                                                          000100AA
      DO                                                                000110AA
        READ (*, '(A1)', IOSTAT=STATUS) C                               000120AA
C      -STATUS -1 IS END OF FILE.-                                      000130AA
        IF (STATUS == -1) EXIT                                          000140AB
        IF (C == '(') THEN                                              000150AB
          FLOOR = FLOOR + 1                                             000160AA
        ELSE IF (C == ')') THEN                                         000170AB
          FLOOR = FLOOR - 1                                             000180AA
        END IF                                                          000190AA
        IF ((BASEMENT .EQV. .FALSE.) .AND. (FLOOR < 0)) THEN            000200AB
          WRITE (*,*) 'BASEMENT ENTERED AT', STEP                       000210AA
          BASEMENT = .TRUE.                                             000220AA
        END IF                                                          000230AA
        STEP = STEP + 1                                                 000240AA
      END DO                                                            000250AA
      WRITE (*,*) 'AT FLOOR', FLOOR                                     000260AA
      END PROGRAM AOC1                                                  000270AA

aoc1.f90

program aoc1
    implicit none

    character :: c
    integer :: status, floor, step
    logical :: basement

    basement = .false.
    floor = 0
    step = 0
    do
        read (*, '(A1)', iostat=status) c
        if (status == -1) exit    ! end of file

        if (c == '(') then
            floor = floor + 1
        else if (c == ')') then
            floor = floor - 1
        end if

        if ((basement .eqv. .false.) .and. (floor < 0)) then
            write (*,*) 'Basement entered at', step
            basement = .true.
        end if

        step = step + 1
    end do

    write (*,*) 'At floor', floor

end program aoc1