#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAX = 2e5 + 10, MOD = 1e9 + 7;
int dp[MAX], dp2[MAX];
void solve() {
vector<pair<int, int>> vt;
map<int, int> mp;
int n;
cin >> n;
int a[n + 1];
int b[n + 1];
for(int i = 1; i <= n; i++) {
cin >> a[i] >> b[i];
vt.push_back({a[i], b[i]});
}
sort(vt.begin(), vt.end());
int pref[n + 1];
pref[0] = 0;
for(int i = 0; i < n; i++) {
pref[i + 1] = pref[i] + vt[i].second;
mp[vt[i].first] = i;
}
sort(a + 1, a + n + 1);
int ans = 0;
int i = 1;
for(int j = i; j <= n; j++) {
int x = mp[a[j]], y = mp[a[i]];
ans = max(ans, pref[x + 1] - pref[y] - (a[j] - a[i]));
}
cout << ans << endl;
}
signed main() {
int t = 1;
//cin >> t;
while(t--) {
solve();
}
}
