https://blog.faceutil.com/2017/04/24/rpg-%ed%85%8c%eb%9d%bc%eb%a6%ac%ec%95%84-1-2-4-1-%ec%b5%9c%ec%8b%a0%eb%b2%84%ec%a0%84-%ec%83%88%eb%a1%9c%ec%9a%b4-%eb%b3%b4%ec%8a%a4-%ec%83%88%eb%a1%9c%ec%9a%b4-%ec%95%84%ec%9d%b4%ed%85%9c/