#include <bits/stdc++.h>
#define ll long long
#define sp << " "
#define faster ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
using namespace std;
ll n, mi=1e18, c[500005], kq=-1e18;
pair<ll,ll> a[500005];
int main(){
faster;
cin >> n;
for(ll i = 1; i <= n; i++){
cin >> a[i].first >> a[i].second;
}
sort(a+1,a+n+1,greater<pair<ll,ll>>());
for(ll i = 1; i <= n; i++) c[i]=c[i-1]+a[i].second;
for(ll i = 1; i <= n; i++){
mi=min(mi,c[i-1]+a[i].first);
kq=max(kq,c[i]+a[i].first-mi);
}
cout << kq;
return 0;
}
