a, b = input(), input()
ans = 'NG'
if a.isnumeric() and b.isnumeric():
    if len(a) == len(list(str(int(a)))) and len(b) == len(list(str(int(b)))):
        if 0<=int(a)<=12345 and 0<=int(b)<=12345:
            ans = 'OK'
print(ans)