import re

A = input()
B = input()

pattern = re.compile('^(0|[1-9]\d*)$')


def check(s):
    if pattern.match(s) and 0 <= int(s) <= 12345:
        return True
    else:
        return False


if check(A) and check(B):
    print('OK')
else:
    print('NG')