#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <vector>
#include <sstream>
#include <queue>
using namespace std;
const int maxn = 1e6;
pair<long long,long long> a[maxn+5];
long long pre[maxn+5];
long long n;
void solve()
{
cin >> n;
for(int i = 1; i <= n; i++)
cin >> a[i].first >> a[i].second;
sort(a+1,a+1+n);
long long minn = -a[1].first;
long long ans = 0;
for(int i = 1; i <= n; i++)
{
pre[i] += a[i].second + pre[i-1];
ans = max(ans,pre[i]-minn-a[i].first);
minn = min(minn,pre[i]-a[i+1].first);
}
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
solve();
return 0;
}
