#include<iostream> #include<cstdio> using namespace std; int main() { //int a,b,c,d,e; //scanf("%1d%1d%1d%1d%1d",&a,&b,&c,&d,&e); //cout<<e<<d<<c<<b<<a; double a,b,c; scanf("%lf%lf%lf",&a,&b,&c); printf("%.2lf",(a+b+c)/3); return 0; }