A = input()
B = input()

def isCheck(s):
    if s.isdigit() == False:
        return False
    if s[0:1] == '0' and s != '0':
        return False
    if(int(s) < 0 or int(s) > 12345):
        return False
    return True

if isCheck(A) and isCheck(B):
    print("OK")
else:
    print("NG")