#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long ll;
ll inf = 100000000000000000;
ll solve(vector<ll> &v){
    ll a = v[0],b = v[1],c = v[2],d = v[3],e = v[4];
    ll l = max({a - e,c - d,0LL}),r = min(a,c);
    ll L = max({(2*a - b + 2*c - d - e + 2)/3,a - b + c - e,a - b + c - d}),R = b;
    bool flag = false;
    ll x = inf;
    l = max(l,L), r = min(r,R);
    if(l<=r) x = l;
    return a + c - x;
}

int main(){
    vector<ll> v;
    int i,j;
    for(i=0;i<5;i++){
        ll a; cin >> a; v.push_back(a);
    }
    ll ans = 0;
    for(i=0;i<5;i++){
        vector<ll> u;
        for(j=i;j<i + 5;j++){
            u.push_back(v[j%5]);
        }
        ans = max(ans,solve(u));
    }
    cout << ans << endl;
}