# -*- coding: utf-8 -*-

def is_int_str(string):
    is_int = None
    try:
        int(string)
        is_int = True
    except ValueError:
        is_int = False
    return is_int

A = input()
B = input()

if is_int_str(A) and is_int_str(B):
    if str(int(A)) == A and str(int(B)) == B:
        print('OK')
    else:
        print('NG')
else:
    print('NG')