#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll, ll>
#define fi first
#define se second
ll N, ps[500100]; //s[500100], v[500100], dps[500100][2], dpmin[500100][2], dpmax[500100][2];
pll a[500100];
int main() {
cin >> N;
for (int i = 1; i <= N; i++) {
cin >> a[i].fi >> a[i].se;
}
sort(a+1, a+N+1);
ps[0] = 0;
for (int i = 1; i <= N; i++) {
ps[i] = ps[i-1] + a[i].se;
}
ll ans = -4e18;
for (int i = 1; i <= N; i++) {
for (int j = i; j <= N; j++) {
ans = max(ans, ps[j]-ps[i-1] - (a[j].fi - a[i].fi));
}
}
cout << ans << endl;
}
