#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ff first
#define ss second
#define pb push_back
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
void afterdot(int n){
cout<<setprecision(n)<<fixed;
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
ll n;
cin>>n;
pair<ll,ll> a[n+2];
for(int i=1;i<=n;i++){
cin>>a[i].ff>>a[i].ss;
}
sort(a+1,a+n+1);
ll ans=0,sum=0;
for(int i=1;i<=n;i++){
sum+=a[i].ss;
ans=max(ans,sum-(a[i].ff-a[1].ff));
}
cout<<ans<<endl;
}
