#include <bits/stdc++.h>
#define int long long
using namespace std;
const long long N = 2e5 + 5;
int a[N];
int dp[N];
void solve()
{
int n, ans;
cin >> n;
vector<pair<int, int>> a(n);
for (int i = 0; i < n; i++)
{
cin >> a[i].first >> a[i].second;
}
sort(a.begin(), a.end(), [&](pair<int, int> a, pair<int, int> b)
{ return a.first < b.first; });
int sum = a[0].second;
ans = sum;
for (int i = 1; i < n; i++)
{
sum = sum - (a[i].first - a[i - 1].first);
if (sum < 0)
sum = 0;
sum += a[i].second;
ans = max(ans, sum);
}
cout << ans << endl;
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
int t = 1;
// cin >> t;
for (int i = 1; i <= t; i++)
{
// cout << "Case #" << i << ':' << ' ';
solve();
cout << endl;
}
return 0;
}
