A = input()
B = input()
if A.isnumeric() and B.isnumeric():
    if int(A) > 12345 or int(B) > 12345:
        print('NG')
    elif (A[0] == '0' and A != '0') or (B[0] == '0' and B != '0'):
        print('NG')
    else:
        print('OK')
else:
    print('NG')