import re

def shapingNumber(number: str) -> str:
    shaping = number
    shaping = re.sub("^0+.+", "", shaping)
    shaping = re.sub("[^0-9]", "", shaping)
    return shaping

def isEqualShapingNumber(original: str) -> bool:
    return original == shapingNumber(original)

def solve():
    a, b = input(), input()
    print("OK" if isEqualShapingNumber(a) and isEqualShapingNumber(b) else "NG")

if __name__=="__main__":
    solve()