#include <iostream>
using namespace std;
int main(){
    int a,b,c,d,e,f;
    cin>>a;
    cin>>b;
    cin>>c;
    cin>>d;
    cin>>e;
    cin>>f;
    float x;
    x=(a+b+c+d+e+f)/6;
    cout<<x;
    return 0;
}