#include <iostream>
#include <cstdio>
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 <= 1) {
        puts("\"assert\"");
        return 1;
    }

    ll max1 = 0, max2 = 0;

    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {

            if (max1 < a[i] + a[j]) {
                max2 = max1;
                max1 = a[i] + a[j];
            }
        }
    }

    cout << max2 << endl;

    return 0;
}