#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
const ll maxN = 5e5+10;
vector<pair<ll, ll>> a;
map<ll, ll> b;
ll n;
int main()
{
ios_base::sync_with_stdio(0);cin.tie(nullptr);
cin>>n;
ll mx = 0;
for(int i = 0; i < n; i++){
ll aa, bb;
cin>>aa>>bb;
a.push_back({aa, bb});
mx=max(mx, bb);
}
for(int i = 0; i < n; i++){
b[a[i].first]+=a[i].second;
}
a.clear();
for(auto i : b){
a.push_back({i.first, i.second});
}
sort(a.begin(), a.end());
n = a.size();
for(int i = 0; i < n; i++){
mx=max(mx, a[i].second);
}
ll cur = a[0].second;
for(int i = 1; i < n; i++){
cur = max(cur+a[i].second-abs(a[i].first-a[i-1].first), a[i].second);
mx=max(mx, cur);
}
cout<<mx;
return 0;
}
