#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define ln '\n'
const int N = 5e5 + 5;
const int LG = 20;
const int INF = 2e9 + 5;
const int MOD = 998244353;
int n;
pair<ll, ll> a[N];
ll pfx[N];
void init(){
cin >> n;
for (int i = 0; i < n; i++){
cin >> a[i].first >> a[i].second;
}
}
ll solve(){
sort(a, a+n);
pfx[0] = a[0].second;
for (int i = 1; i < n; i++) pfx[i] = pfx[i-1] + a[i].second;
ll ans = 0LL, mx = 0LL;
for (int i = 0; i < n; i++){
mx = max(mx, a[i].first - ((i-1 < 0)? 0LL: pfx[i-1]));
ans = max(ans, pfx[i] + mx - a[i].first);
}
return ans;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// freopen("mooyomooyo.in", "r", stdin);
// freopen("mooyomooyo.out", "w", stdout);
// ll T; cin >> T;
// while (T--){
// solve();
// }
init();
cout << solve();
return 0;
}
