#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <string>
#include <vector>
using namespace std;

int main() {
	int N, i;
	cin >> N;
	scanf("%*c");
	string A1;
	getline(cin, A1);
	for (i = 0; i < A1.size(); ++i) {
		if (' ' == A1[i]) break;
	}
	if (A1.size() == i) {
		vector<long> A(3, stol(A1)), a;
		for (i = 1; i < A.size(); ++i) cin >> A[i];
		for (i = 0; i < 2; ++i) {
			for (int j = 1 + i; j < 3; ++j) a.push_back(A[i] + A[j]);
		}
		sort(a.begin(), a.end(), greater<long>());
		a.erase(a.begin(), unique(a.begin(), a.end()));
		cout << a[1];
	}
	else cout << "assert";
}