https://blog.faceutil.com/2017/10/17/50%ec%9b%90%ec%a7%9c%eb%a6%ac-%ec%98%a4%eb%9d%bd%ec%8b%a4-%ea%b2%8c%ec%9e%84%ec%9d%98-%ec%b6%94%ec%96%b5-3-ozma-wars-%ec%99%b8-%e3%82%b1/