#include <bits/stdc++.h>

using namespace std;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl;
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
typedef long long ll;
#define int ll
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(int)(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
#define Sp(p) cout<<setprecision(25)<< fixed<<p<<endl;
// int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
// int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
// vi dx2 = { 1,1,0,-1,-1,-1,0,1 }, dy2 = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
const ll MOD = 1000000007;
// const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'

int f(ll k, ll x, vl &a) {
    vl b = a;
    rep (i, 5) b[i] -= k;

    vl op;
    op.push_back(x);
    ll sum = x;
    rep (i, 3) {
        ll pre = op.back();
        ll nex;
        if (b[i + 1] + pre >= 0) nex = 0;
        else nex = -b[i + 1] - pre;
        op.push_back(nex);
        sum += nex;
    }
    if (sum > k) {
        return 1;
    }
    ll add = k - sum;
    ll l1 = b[0] + x + add, l2 = b.back() + op.back() + add;
    if (l1 >= 0 and l2 >= 0) return 0;
    else if (l1 >= l2) return 1;
    else return -1;
}

bool check(ll k, vl& a) {
    ll small = 0, large = k;
    if (f(k, small, a) == 0 or f(k, large, a) == 0) return true;
    while (small + 1 < large) {
        ll mid = (small + large) / 2;
        ll res = f(k, mid, a);
        if (res == 0) return true;
        else if (res == 1) large = mid;
        else small = mid;
    }
    return false;
}

signed main() {
    fio();
    
    vl a(5);
    rep (i, 5) cin >> a[i];

    ll ok = 0, ng = INF;
    while (ok + 1 < ng) {
        ll mid = (ok + ng) / 2;
        if (check(mid, a)) ok = mid;
        else ng = mid;
    }
    cout << ok << endl;
}