#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int main(){
    vi S(6);
    while(cin>>S[0]){
        FOR(i,1,6){
            cin >> S[i];
        }
        sort(all(S));
        ll ans = 0;
        FOR(i, 1, 5){
            ans += S[i];
        }
        ans = ans * 100 / 4;
        printf("%lld.%02lld\n", ans / 100, ans % 100);
    }
}