#include <bits/stdc++.h>
using namespace std;
using ll=long long;
ll compute(ll sum,ll min,ll max){
return sum-(max-min);
}
int main(){
int n;
cin>>n;
vector<pair<ll,ll>> paintings(n);
for (int i=0;i<n;i++){
ll a,b;
cin>>a>>b;
paintings[i]={a,b};
}
sort(paintings.begin(),paintings.end());
vector<ll> prefix(n);
prefix[0]=paintings[0].second;
for (int i=1;i<n;i++) prefix[i]=prefix[i-1]+paintings[i].second;
ll ans=LLONG_MIN;
ll minn=LLONG_MAX;
for (int i=0;i<n;i++){
if (i==0) minn=min(minn,-paintings[i].first);
else minn=min(minn,prefix[i-1]-paintings[i].first);
ans=max(ans,prefix[i]-paintings[i].first-minn);
}
cout<<ans;
return 0;
}
