#include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int n, m = 0;     cin >> n;     while (n--) {       int x, y;       cin >> x >> y;       m = max(m, x + y);     }     cout << m;     return 0;   }   