#include<bits/stdc++.h>
using namespace std;
#define int long long
#define in pair<int, int>
#define f first
#define s second
#define pb push_back
#define pob pop_back
#define INF (int)1e17
#define MX (int)3e5+5
#define fast() ios_base::sync_with_stdio(false); cin.tie(NULL)
signed main()
{
fast();
int n;
cin >> n;
vector<in> ab(n+1);
for(int i = 1; i <= n; i++)
cin >> ab[i].f >> ab[i].s;
sort(ab.begin()+1, ab.end());
ab[0] = {0,0};
for(int i = 1; i <= n; i++)
ab[i].s+=ab[i-1].s;
int ans = -INF;
int mn = INF;
for(int i = 1; i <= n; i++)
{
mn = min(mn, ab[i-1].s-ab[i].f);
ans = max(ans, ab[i].s-ab[i].f-mn);
}
mn = INF;
cout << ans << "\n";
return 0;
}
