#include <bits/stdc++.h>   using namespace std;   int main() {     long long n;     cin >> n;     long long maxi = LLONG_MIN;     for (long long i = 1LL; i <= n; i++) {       long long x, y;       cin >> x >> y;       maxi = max(maxi, x + y);     }     cout << maxi << endl;   }   