#include <iostream>
#include <iomanip>
using namespace std;
int main(){
    int mx = -1;
    int mn = 101;
    int sm  =0;
    for(int i = 0; 6 > i; i++){
        int t;cin>>t;
        sm += t;
        mn = min(mn,t);
        mx = max(mx,t);
    }
    cout << fixed << setprecision(10) << (double)(sm-mn-mx)/4 << endl;
}