#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int a[6];
    rep(i,6)cin >> a[i];
    sort(a, a+6);
    int sum = 0;
    srep(i,1,5)sum += a[i];
    cout << sum / 4 << '.';
    cout << setfill('0') << right << setw(2) << sum % 4 * 25 << endl;
    return 0;
}