#include <bits/stdc++.h>
#define ff first
#define ss second
using namespace std;
const long long INF = 0xf3f3f3f3f3f3f3f;
const int maxn = 5e5 + 5;
pair<long long, long long> arr[maxn];
void solve() {
int n;
cin >> n;
for (int i = 1; i <= n; i++)
cin >> arr[i].ff >> arr[i].ss;
sort(arr + 1, arr + 1 + n);
for (int i = 2; i <= n; i++)
arr[i].ss += arr[i-1].ss;
long long mi = -arr[1].ff;
long long ans = arr[1].ss;
for (int i = 1; i <= n; i++) {
ans = max(ans, arr[i].ss - arr[i].ff - mi);
mi = min(mi, arr[i].ss - arr[i+1].ff);
}
cout << ans << '\n';
}
signed main() {
solve();
return 0;
}
