# coding: utf-8
# Here your code !
A = input()
B = input()

if not A.isnumeric() or not B.isnumeric(): # 数字以外を含むか
    print("NG")
elif (A != "0" and A[0] == "0") or (B != "0" and B[0] == "0"): # 0でないのに0から始まるか
    print("NG")
elif (0 <= int(A) <= 12345) and (0 <= int(B) <= 12345): # 0 <= A,B <= 12345を満たすか
    print("OK")
else:
    print("NG")