#include <iostream>
#include <vector>
#include <algorithm>
#include <unordered_set>
#include <cstring>
#include <array>
#include <cmath>
#include <stack>
#include <queue>
#include <map>
#include <set>
#define INF 1e6
using namespace std;
typedef long long ll;
const ll MOD = 1000000007;
const ll MAXN = 1005;
void solve()
{
int n; cin >> n;
vector<pair<ll, ll>>v(n + 1);
for (int i = 1; i <= n; i++) {
cin >> v[i].first >> v[i].second;
}
sort(v.begin(), v.end());
for (int i = 1; i <= n; i++) {
v[i].second += v[i - 1].second;
}
ll ans = 0;
for (int i = 1; i <= n; i++) {
for (int j = 1; j < i; j++) {
ll sum = v[i].second - v[j - 1].second;
sum -= v[i].first - v[j].first;
ans = max(ans, sum);
}
}
cout << ans << "\n";
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;// cin >> t;
while (t--) solve();
return 0;
}
