PROGRAM FRONT
      INTEGER FACT,I,J
      DO 1 I=-2,10
        J=FACT(I)
        PRINT 100,I,J
1     CONTINUE
100   FORMAT(1X,I4,' FACTORIAL IS ',I10)
      END
      INTEGER FUNCTION FACT(N)
      INTEGER N,I
      FACT=1
C
C THERE ARE THREE CASES.
C 1) N > 1 FACTORIAL EVALUATED
C 2) N = 0 OR N = 1 FACTORIAL IS 1
C 3) N < 0 FACTORIAL ILLEGAL
C
      IF(N.LT.0)THEN
        PRINT *,' NEGATIVE VALUE FOR FACTORIAL'
        PRINT *,' NOT DEFINED'
        FACT = 0
      ELSE
        DO 1 I = 2,N
          FACT = FACT*I
1       CONTINUE
      ENDIF
      END