def isok(S):
    if S[0] == "0" and len(S) != 1:
        return False
    cnt = 0
    for i in range(10):
        cnt += S.count(str(i))
    if cnt != len(S):
        return False
    if 0 <= int(S) <= 12345:
        return True
    else:
        return False
    
A = input()
B = input()
if isok(A) and isok(B):
    print("OK")
else:
    print("NG")