!-----  Ex3_1: 成績チェック   -----
      INTEGER :: n, s, k
      s = 0; k = 0
   10 PRINT*,'Input mark for each student (or negative one to quit):'
      READ*, n;   IF(n<0) GOTO 999
      s = s + 1
      IF(n >= 60) k = k + 1
      GOTO 10
  999 PRINT*, k,' students passed in this exam. Total =', s
      END