#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
int main() {
  long long T = 1;
  while (T--) {
    long long n;
    cin >> n;
    long long mx = 0;
    pair<int, int> win;
    for (int i = 0; i < n; i++) {
      long long x, y;
      cin >> x >> y;
      if (mx < x + y) {
        win.first = x;
        win.second = y;
        mx = x + y;
      }
    }
    cout << win.second - (-win.first) << endl;
  }
}
