#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#define ll unsigned long long
#define double double long
#define fori(i,j,k) for(ll i=j; i<=k;i++)
#define study ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define pb push_back
#define all(s) s.begin(),s.end()
#define ins insert
#define ss second
#define ff first
#ifndef DB
#define DB 0
#endif
#define debugl(l) if constexpr((l)<DB)
#define debug debugl(0)
const ll sz=1e6+10;
ll INF=1e9;
ll mod=1e9+7;
ll add=1e6;
void work(){
ll n;
cin>>n;
vector<pair<ll,ll>>v(n);
fori(i,0,n-1){
cin>>v[i].ff>>v[i].ss;
}
sort(all(v));
ll ans=0;
fori(i,0,n-2){
ll cur=0;
cur+=v[i].ss;
fori(j,i+1,n-1){
cur+=v[j].ss;
if((v[j].ff>=v[i].ff))
ans=max(ans,cur-(v[j].ff-v[i].ff));
}
}
cout<<ans<<endl;
}
int main()
{
//#ifndef LOCAL
// freopen("log1.txt","r",stdin);
// freopen("log2.txt","w",stdout);
//#endif
study;
ll t=1;
//cin>>t;
fori(i,1,t){
work();
}
}
