! 最大公約数を求める
PROGRAM ex5_5

  IMPLICIT NONE
  INTEGER :: m, n, k

  PRINT '(1X, A)', 'Input two integers m, n (>0): '
  READ *, m, n

  IF ( m > 0 .AND. n > 0 ) THEN
    DO
      k = MOD( m, n )
      IF ( k == 0 ) EXIT
      m = n
      n = k
    END DO

    IF ( n > 1 ) THEN
      PRINT '(1X, A, I10)', '最大公約数 = ', n
    ELSE
      PRINT '(1X, A)', '公約数なし'
    END IF
  END IF

END PROGRAM ex5_5