! bubble sorting
PROGRAM ex7_4

  IMPLICIT NONE
  INTEGER :: num, n, m
  CHARACTER(LEN=15) :: word(1:100), wtemp

  DO num = 1, 100
    PRINT '(1X, A)', 'Input a word: '
    READ '(A)', wtemp
    IF ( wtemp == "" ) EXIT
    word(num) = wtemp
  END DO

  num = num - 1
  DO n = num, 2, -1
    DO m = 1, n - 1
      IF ( word(m) > word(m+1) ) THEN
        wtemp = word(m)
        word(m) = word(m+1)
        word(m+1) = wtemp
      END IF
    END DO
  END DO

  DO n = 1, num
    PRINT '(1X, A)', word(n)
  END DO

END PROGRAM ex7_4