#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  int n;
  cin >> n;
  
  vector<ll> l(n), r(n);
  for (int i = 0; i < n; i++) {
    ll a, b;
    cin >> a >> b;
    l[i] = a - b;
    r[i] = b - a;
  }
  
  for (int i = 1; i < n; i++) l[i] += l[i - 1];
  for (int i = n - 2; i >= 0; i--) r[i] += r[i + 1];
  
  ll ans = max(l[n - 1], r[0]);
  for (int i = 0; i < n - 1; i++) ans = max(ans, l[i] + r[i + 1]);
  
  cout << ans << '\n';
}