PROGRAM FIVE_WEEKENDS

DIM M$[12]

PROCEDURE MODULO(X,Y->MD)
  IF Y=0 THEN
     MD=X
   ELSE
     MD=X-Y*INT(X/Y)
  END IF
END PROCEDURE

PROCEDURE WD(M,D,Y->RES%)
  IF M=1 OR M=2 THEN
     M+=12
     Y-=1
  END IF
  MODULO(365*Y+INT(Y/4)-INT(Y/100)+INT(Y/400)+D+INT((153*M+8)/5),7->RES)
  RES%=RES+1.0
END PROCEDURE

BEGIN
  M$[]=("","JANUARY","FEBRUARY","MARCH","APRIL","MAY","JUNE","JULY","AUGUST","SEPTEMBER","OCTOBER","NOVEMBER","DECEMBER")
  PRINT(CHR$(12);) ! CLS
  FOR YEAR=1900 TO 2100 DO
       FOREACH MONTH IN (1,3,5,7,8,10,12) DO   ! months with 31 days
           WD(MONTH,1,YEAR->RES%)
           IF RES%=6 THEN  ! day #6 is Friday
              PRINT(YEAR;": ";M$[MONTH])
              CNT%=CNT%+1
!             IF CNT% MOD 20=0 THEN GET(K$) END IF  ! press a key for next page
            END IF
       END FOR
  END FOR
  PRINT("Total =";CNT%)
END PROGRAM