A = input()
B = input()

if not A.isdigit() or not B.isdigit():
    print("NG")
elif not (0 <= int(A) <= 12345) or not (0 <= int(B) <= 12345):
    print("NG")
elif (len(A) >= 2 and A[0] == "0") or (len(B) >= 2 and B[0] == "0"):
    print("NG")
else:
    print("OK")