#include <bits/stdc++.h>
#define int int64_t
#define ii pair<int , int>
#define fi first
#define se second
#define FOR(i , l , r) for(int i = l ; i <= r ; i++)
#define FORD(i , r , l) for(int i = r ; i >= l ; i--)
using namespace std;
const int N = 2e5;
int n , res;
int pre[N + 2];
priority_queue<int> que;
ii a[N + 2];
signed main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
FOR(i , 1 , n) cin >> a[i].fi >> a[i].se;
sort(a + 1 , a + n + 1);
FOR(i , 1 , n) pre[i] = pre[i - 1] + a[i].se;
que.push(0);
FOR(i , 1 , n)
{
que.push(a[i].fi - pre[i - 1]);
res = max(res , pre[i] - a[i].fi + que.top());
}
cout << res;
}
