#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)
using ll = long long;
#define all(p) p.begin(),p.end()

int main(){
	int N=5;
	vector<ll> p(N);
	rep(i,0,N) cin>>p[i];
	ll l_ans=0,r_ans=3e15;
	vector<vector<int>> A={
		{0,2,4},
		{0,3},
		{1,3},
		{1,4}
	};
	while(r_ans-l_ans>1){
		ll med_ans=(l_ans+r_ans)/2;
		vector<ll> q(5);
		rep(i,0,5) q[i]=max(0ll,med_ans-p[i]);
		ll sum=q[0]+q[2]+q[4];
		ll op=med_ans;
		bool ok=1;
		if(sum>med_ans){
			ll tmp=sum-med_ans;
			if(min(q[0],q[4])<tmp){
				ok=0;
			}
			else q[0]-=tmp,q[4]-=tmp,op-=tmp;
		}
		for(auto x:A){
			sum=0;
			for(auto y:x) sum+=q[y];
			if(sum>op) ok=0;
		}
		if(ok) l_ans=med_ans;
		else r_ans=med_ans;
	}
	cout<<l_ans<<"\n";
}