#include <iostream>
#include <algorithm>
#include <cstdio>
#include <vector>
using namespace std;
using ll = long long;

int main()
{
    ll n;
    ll a[3];
    ll line = 0;

    scanf("%lld", &n);
    for (int i = 0; i < n; i++) {
        scanf("%lld", a + i); 
        char ch = getchar();

        if (ch == '\n') {
            line++;
        }
    }

    if (line != 3) {
        puts("\"assert\"");
        return 0;
    }

    vector<ll> x;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (i == j) continue;

            x.push_back(a[i] + a[j]);
        }
    }

    sort(x.begin(), x.end());
    x.erase(unique(x.begin(), x.end()), x.end());

    cout << x[x.size() - 2] << endl;

    return 0;
}