#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define fi first
#define se second
const int MAXN=5e5+5;
const ll inf=2e18;
int n;
pll pref[MAXN+1];
int main(){
// freopen("input","r",stdin);
// freopen("output","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n;
for(int i=1;i<=n;i++){
cin>>pref[i].fi>>pref[i].se;
}
sort(pref+1,pref+n+1,[&](pll x,pll y){
if(x.fi==y.fi){
return x.se>y.se;
}
return x.fi<y.fi;
});
ll sum=0,ans=-inf,mn=0;
for(int i=1;i<=n;i++){
mn=min(mn,sum-pref[i].fi);
sum+=pref[i].se;
ans=max(ans,sum-pref[i].fi-mn);
}
cout<<ans;
}
