#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < n; ++i)
#define rep3(i, l, n) for (int i = l; i < n; ++i)
#define chmax(a, b) a = (a >= b ? a : b)
#define chmin(a, b) a = (a <= b ? a : b)
#define out(a) cout << a << endl
#define outa(a, n) rep(_, n) cout << a[_] << " "; cout << endl
#define SZ(v) (int)v.size()
#define inf (int)(1e9+7)
#define abs(x) (x >= 0 ? x : -(x))

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    cin.ignore();
    string s;
    getline(cin, s);
    // out(SZ(s));
    if (regex_search(s, regex(" "))) { out("assert"); return 0; }
    ll a = stoi(s);
    ll b, c;
    cin >> b >> c;
    vector<ll> v;
    v.eb(a + b);
    v.eb(b + c);
    v.eb(c + a);
    sort(all(v));
    if (v[0] == v[1] && v[1] == v[2]) out("assert");
    else if (v[2] == v[1]) out(v[0]);
    else out(v[1]);
}