#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=5e5+5;
int n,sum,ans,pos,mn=1e16,mx;
pair <int,int> a[N];
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for(int i=1;i<=n;i++) cin >> a[i].first >> a[i].second;
sort(a+1,a+1+n);
ans=sum=a[1].second;
mn=mx=a[1].first;
for(int i=2;i<=n;i++){
if(sum+a[i].second-(a[i].first-mn)>=a[i].second){
sum+=a[i].second;
ans=max(ans,sum-(a[i].first-mn));
}
else{
sum=a[i].second;
mn=a[i].first;
ans=max(ans,sum-(a[i].first-mn));
}
}
cout << ans;
}
