#include <bits/stdc++.h>
using namespace std;
const long long MAX = 5e5 + 5;
pair<long long, long long> a[MAX];
long long pref[MAX], dp[MAX];
void solve()
{
long long n;
cin >> n;
for (long long i = 1; i <= n; i++)
cin >> a[i].first, cin >> a[i].second;
sort(a + 1, a + n + 1);
for (long long i = 1; i <= n; i++)
pref[i] = pref[i - 1] + a[i].second;
for (long long i = 1; i <= n; i++)
{
dp[i] = max(a[i].second, dp[i - 1] + a[i].second - (a[i].first - a[i - 1].first));
}
long long mx = -1;
for (long long i = 1; i <= n; i++)
mx = max(dp[i], mx);
cout << mx;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
long long tt = 1;
// cin >> tt;
while (tt--)
solve();
return 0;
}
