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

    Uc = [chr(i) for i in range(65, 65 + 26)] #UpperCase
    Lc = [chr(i) for i in range(97, 97 + 26)] #LowerCase

    f = 0
    if f == 0:
        for a in A:
            if a in Uc or a in Lc:
                f = 1
                break

    if f == 0:
        for b in B:
            if b in Uc or b in Lc:
                f = 1
                break

    if f == 0:
        if len(A) > 1:
            if A[0] == "0":
                f = 1
        if len(A) > 1:
            if B[0] == "0":
                f = 1

    if f == 0:
        if 0 <= int(A) <= 12345 and 0 <= int(B) <= 12345:
            pass
        else:
            f = 1

    if f == 0:
        print("OK")
    else:
        print("NG")

if __name__ == "__main__":
    main()