#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<vector>
#include<map>
#include<set>
#include<string>
#include<queue>
#include<stack>
#include<complex>
using namespace std;
#define MOD 1000000007
#define MOD2 998244353
#define INF (1<<29)
#define LINF (1LL<<60)
#define EPS (1e-10)
#define PI 3.1415926535897932384626433832795028
typedef long long Int;
typedef pair<Int, Int> P;
typedef long double Real;
typedef complex<Real> CP;

Int A, B, C, D, E;

bool ok(Int x){
    Int a = A - 3*x;
    Int b = B - 3*x;
    Int c = C - 3*x;
    Int d = D - 3*x;
    Int e = E - 3*x;
    
}

int main(){
    cin >> A >> B >> C >> D >> E;
    Int bottom = 0;
    Int top = A + B + C + D + E;
    while(top - bottom > 1){
        Int mid = (top + bottom ) / 2;
        if(ok(mid))bottom = mid;
        else top = mid;
    }
    cout << bottom << endl;
    return 0;
}