#include <bits/stdc++.h>
#define ll long long
#define ii pair<ll,ll>
#define fi first
#define se second
using namespace std;
const int N=5e5+6;
const ll inf=1e18;
int n;
vector<ii>v(N);
ll pre[N];
ll tong=-inf,tong1=inf;
int main()
{
cin >>n;
for(int i=1;i<=n;i++){
cin >> v[i].fi >> v[i].se;
}
sort(v.begin()+1,v.begin()+1+n);
for(int i=1;i<=n;i++){
pre[i]=pre[i-1]+v[i].se;
}
tong1=pre[0]-v[1].fi;
for(int i=1;i<=n;i++){
tong=max(tong,pre[i]-v[i].fi-tong1);
tong1=min(tong1,pre[i]-v[i+1].fi);
}
cout << tong;
return 0;
}
