#!/usr/bin/env python3


def validate(a, b):
    try:
        a0 = int(a)
        b0 = int(b)
    except ValueError:
        return False
    else:
        if (a0 and a.startswith("0")) or (b0 and b.startswith("0")):
            return False
        elif (not a0 and len(a) > 1) or (not b0 and len(b) > 1):
            return False
        else:
            return 0 <= a0 <= 12345 and 0 <= b0 <= 12345


def main():
    a = input()
    b = input()
    if validate(a, b):
        print("OK")
    else:
        print("NG")


if __name__ == '__main__':
    main()