#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define OYY 100000000000005
#define mod 1000000007
#define faster ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define FOR for(int i=1;i<=n;i++)
#define mid (start+end)/2
#define lim 300005
#define fi first
#define se second
vector<pair<int,int>> v;
int32_t main(){
faster
int n;cin>>n;
FOR{
int x,y;cin>>x>>y;
v.push_back({x,y});
}
sort(v.begin(),v.end());
int cev=0;
vector<int> pre(n+1,0);
FOR{
pre[i]=pre[i-1]+v[i-1].se;
}
FOR{
for(int j=i;j<=n;j++){
cev=max(cev,pre[j]-pre[i-1]-(v[j-1].fi-v[i-1].fi));
}
}
cout<<cev<<'\n';
return 0;
}
