#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int MOD = 998244353;
void solve() {
int n; cin >> n;
vector<ll> a(n), b(n);
for (int i=0; i<n; i++) {
cin >> a[i] >> b[i];
}
ll ans=0;
for (int i=0; i<n; i++) {
for (int j=0; j<n; j++) {
if (a[i] > a[j]) continue;
ll sum=0;
for (int k=0; k<n; k++) {
if (a[i] <= a[k] && a[k] <= a[j]) {
sum += b[k];
}
}
ans = max(ans, sum-(a[j]-a[i]));
}
}
cout << ans << "\n";
}
//1 2 3 4 0
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
while (t--) {
solve();
}
return 0;
}
