REM Long year
CLS
PRINT "****     List of ISO long years     ****"
PRINT "Start year";
INPUT S
PRINT "End year";
INPUT E
PRINT
FOR Y = S TO E
  GOSUB CALCLY:
  IF LY <> 0 THEN
    PRINT Y;
  ENDIF
NEXT Y
PRINT
END

CALCLY:
  REM Nonzero if Y is long
  LY = 0
  AY = Y
  GOSUB CALCWD:
  IF WD = 4 THEN
    LY = -1
  ENDIF
  AY = Y - 1
  GOSUB CALCWD:
  IF WD = 3 THEN
    LY = -1
  ENDIF
RETURN

CALCWD:
  REM Weekday of AY-12-31, 0 = Sunday
  WD = AY
  TMP = AY / 4
  WD = WD + TMP
  TMP = AY / 100
  WD = WD - TMP
  TMP = AY / 400
  WD = WD + TMP
  WD = WD MOD 7
RETURN