#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define FOR(i, x, y) for (int i = x; i < y; i++)
typedef long long ll;
using namespace std;
pair<ll, ll> a[500001];
ll pref[500001];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll n;
cin >> n;
FOR(i, 1, n + 1) cin >> a[i].first >> a[i].second;
sort(a + 1, a + n + 1);
pref[0] = 0;
FOR(i, 1, n + 1) pref[i] = pref[i - 1] + a[i].second;
ll l = 1;
ll ans = a[1].second;
FOR(i, 2, n + 1) {
ll diff = a[i].first - a[i - 1].first + a[i].second;
while (diff < 0) diff += a[l++].second;
ans = max(ans, (pref[i] - pref[l - 1]) - (a[i].first - a[l].first));
}
cout << ans;
return 0;
}
