#include<iostream> #include<cstdio> #include<cstring> #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ double yu,shu,ying,a; cin>>yu>>shu>>ying; a=(yu+shu+ying)/3; printf("%.2lf",a); return 0; }