#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf()\double #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int a,b,c; cin>>a>>b>>c; printf("%.2lf",(a+b+c)/3.0); return 0; }