#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
using namespace std;
const int N = 5005000;
const int MAXN = (5e8);
const int MOD = (1e9) + 7;
const long long INF = (1e17) + 777;
long long n, x, y, mx = -1000;
long long ans;
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> x >> y;
    mx = max(mx, x + y);
    if (mx == x + y) ans = x + y;
  }
  cout << ans;
  return 0;
}
