#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pll pair<ll, ll>
#define fi first
#define se second
#define speed ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int main() {
speed;
int n;
cin >> n;
vector<pll> a(n);
for(int i = 0; i < n; i++) cin >> a[i].fi >> a[i].se;
sort(begin(a), end(a));
ll pref[n+1]{};
pref[0] = a[0].se;
ll ans = 0ll;
for(int i = 1; i < n; i++) pref[i] = a[i].se + pref[i-1];
for(int i = 0; i < n; i++) {
for(int j = 0; j <= i; j++) {
ans = max(ans, pref[i] - (j ? pref[j-1] : 0ll) - (a[i].fi - a[j].fi));
}
}
cout << ans;
}
