#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define all(a) (a).begin(), (a).end()
template<typename T>
int len(T &a){return a.size();}
int main(){
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int n; cin >> n;
vector<ll> a(n), b(n);
for(int i = 0; i < n; i ++){
cin >> a[i] >> b[i];
}
vector<int> p(n); iota(all(p),0);
sort(all(p), [&](int i, int j){return a[i] < a[j];});
vector<ll> val(n);
ll cur = 0;
for(int i = 0; i < n; i ++){
cur += b[p[i]];
if(i > 0) cur -= a[p[i]] - a[p[i - 1]];
val[i] = cur;
}
vector<ll> mx(n);
mx[n - 1] = val[n - 1];
for(int i = n - 2; i >= 0; i --){
mx[i] = max(val[i], mx[i + 1]);
}
ll ans = 0; cur = 0;
for(int i = 0; i < n; i ++){
ans = max(ans, mx[i] - cur);
cur += b[p[i]];
if(i < n - 1) cur -= a[p[i + 1]] - a[p[i]];
}
cout << ans;
return 0;
}
