from collections import defaultdict


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

    if A.isnumeric() and B.isnumeric():
        if 0 <= int(A) <= 12345 and 0 <= int(B) <= 12345:
            if len(A) != 1 and A[0] == "0":
                pass
            elif len(B) != 1 and B[0] == "0":
                pass
            else:
                print("OK")
                return
    print("NG")


if __name__ == '__main__':
    main()