def main():
    A = input()
    B = input()

    try:
        A_num = int(A)
    except ValueError:
        print("NG")
        return

    try:
        B_num = int(B)
    except ValueError:
        print("NG")
        return

    if A != str(A_num) or B != str(B_num):
        print("NG")
        return

    print("OK")


if __name__ == "__main__":
    main()