import math
A = input()
B = input()

A2 = A + "1"
B2 = B + "1"

if A.isdecimal() and B.isdecimal():
    if int(math.log10(int(A2))+1) != len(list(A2)) and int(A) != 0:
        print("NG")
        exit()
    if int(math.log10(int(B2))+1) != len(list(B2)) and int(B) != 0:
        print("NG")
        exit()

    if int(A) <= 12345 and int(B) <= 12345:
        print("OK")
        exit()
print("NG")