import sys

A= input()
B = input()

n = 'NG'
o = 'OK'

if A[0] == '0' or B[0] == '0':
    print(n)
    exit()
for i in A:
    if not ('0' <= i <= '9'):
        print(n)
        exit()
for i in B:
    if not ('0' <= i <= '9'):
        print(n)
        exit()
A = int(A)
B = int(B)
if not (0 <= A <= 12345):
    print(n)
    exit()
if not (0 <= B <= 12345):
    print(n)
    exit()
print(o)