#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
const ll mod = 1e9 + 7;
vector<ll> pf;
ll sum(int l, int r){
if(l == 0) return pf[r];
return pf[r] - pf[l - 1];
}
int main(){
int n;
cin >> n;
vector<pair<ll, ll>> v(n);
for(auto& i : v){
cin >> i.first >> i.second;
}
sort(begin(v), end(v));
pf.resize(n);
pf[0] = v[0].second;
for(int i = 1; i < n; ++i){
pf[i] = pf[i - 1] + v[i].second;
}
ll sol = 0;
for(int i = 0; i < n; ++i){
for(int j = i; j < n; ++j){
sol = max(sol, sum(i, j) - (v[j].first - v[i].first));
}
}
cout << sol << endl;
return 0;
}
