A = []
A.append(input())
A.append(input())
ans = True

for a in A:
    if (
        set(list(a)) - set(list("0123456789")) == set()
        and str(int(a)) == a
        and 0 <= int(a) <= 12345
    ):
        continue
    else:
        ans = False
print("OK" if ans else "NG")