#!/usr/bin/env python
#coding:UTF-8

A = raw_input()
B = raw_input()
ad = str(A)
bd = str(B)
x = isinstance(A,int)
y = isinstance(B,int)
if(x == true and y == true):
     if(ad[0] == '0' or bd[0] == '0'):
          sw = 1
     else:
          sw = 0
else:
     sw = 1

if(sw == 0):
     print("OK")
else:
     print("NG")