def judge(strnum):
    if strnum.isdigit():
        num = int(strnum)
        #print(strnum.zfill(len(strnum)))
        if num <= 12345 and 0 <= num and strnum.zfill(len(strnum)) == strnum:
            return True
        else:
            return False

a = input()
b = input()
if judge(a) and judge(b):
    print("OK")
else:
    print("NG")