def check(a):
    if any(not ai.isdigit() for ai in a):
        return False
    x = int(a)
    if (x and a[0]=="0"):
        return False
    if x==0 and len(a)>=2:
        return False
    return 0 <= x <= 12345

a = input()
b = input()
print("OK" if check(a) and check(b) else "NG")