#include <bits/stdc++.h>
using namespace std;
// psm[i] - psm[j - 1] - (arr[i] - arr[j])
// psm[i] - arr[i] - (-arr[j] + psm[j - 1])
const int DIM = 500005;
pair<long long, long long> arr[DIM];
int main(void) {
#ifdef HOME
freopen("art.in", "r", stdin);
freopen("art.out", "w", stdout);
#endif
int n; cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> arr[i].first >> arr[i].second; }
sort(arr + 1, arr + n + 1);
long long mn = 1LL << 60, mx = -1LL << 60;
for (int i = 1; i <= n; ++i) {
arr[i].second += arr[i - 1].second;
mn = min(mn, -arr[i].first + arr[i - 1].second);
mx = max(mx, arr[i].second - arr[i].first - mn); }
cout << mx;
return 0; }
