#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) begin(x), end(x)
#define inf (int)3e18
#define ff first
#define ss second
#define mem(x, y) fill(begin(x), end(x), y)
using vi = vector<int>;
using vpii = vector<pair<int, int>>;
using vvi = vector<vector<int>>;
using pii = pair<int, int>;
const int MAX = 5e5 + 5;
pii a[MAX];
int pref[MAX];
void solve()
{
int n;
cin >> n;
for (int i = 1; i <= n; i++)
cin >> a[i].ff, cin >> a[i].ss;
sort(a + 1, a + n + 1);
for (int i = 1; i <= n; i++)
pref[i] = pref[i - 1] + a[i].ss;
int mx = 0;
for (int l = 1; l <= n; l++)
{
for (int r = l + 1; r <= n; r++)
{
int sum = pref[r] - pref[l - 1] - a[r].ff + a[l].ff;
mx = max(mx, sum);
}
}
cout << mx;
}
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
int tt = 1;
// cin >> tt;
while (tt--)
solve();
}
