#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <iomanip>
#include <math.h> 
#include <stack>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <tuple>
#include <cctype>
#include <ctype.h>
#include <set>
#include <sstream>
#include <time.h>
#include <numeric>
using namespace std;
//#define int long long
#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define fi first
#define se second
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))
#define l1 list[index]
#define l2 list[index - 1]
#define l3 list[index + 1]
#define iif(i,j) ((i<0 && j<0) || (i>0 && j>0)) ? true : false 
typedef long long ll;
typedef pair<int, int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
typedef pair<pint, int> P1;
typedef pair<int, pint> P2;
typedef pair<pint, pint> PP;
static const ll maxLL = (ll)1 << 62;
const ll MOD = 1000000007;
const ll INF = 1e18;
const double PI = 3.14159265359;
int ca[12] = { 31,28,31,30,31,30,31,31,30,31,30,31 };



signed main() {
	int N;
	vector<ll>list;

	cin >> N;

	for (int i = 0; i <= 3; i++) {

		vector<string> in;
		string line;

		if (getline(cin, line)) {
			istringstream ss(line);
			string a;
			while (ss >> a) {
				in.push_back(a);
				list.push_back(stoll(a));
			}

		}

		if (in.size() >= 2) {
			cout << "\"assert\"" << endl;
			return 0;
		}
	}

	vector<ll>list2;

	list2.push_back(list[0] + list[1]);
	list2.push_back(list[0] + list[2]);
	list2.push_back(list[1] + list[2]);
	
	sort(list2.begin(), list2.end(), greater<ll>());

	if (list2[0] == list2[1]) {
		cout << list2[2] << endl;
	}
	else if (list2[1] == list2[2]) {
		cout << list2[1] << endl;
	}
	else {
		cout << list2[1] << endl;
	}


	return 0;
}