#include<bits/stdc++.h> using namespace std; pair <long long,long long> a[500100]; long long best[500100]; long long n; int main(){ ios_base::sync_with_stdio(0);cin.tie(nullptr);cout.tie(nullptr); cin>>n; for (long long i = 1;i <= n;i ++){ cin>>a[i].first>>a[i].second; } sort(a+1,a+1+n); for (long long i = 1;i <= n;i ++){ a[i].second += a[i-1].second; } for (long long i = n;i >= 1;i --){ best[i] = a[i].second - a[i].first; if (i < n)best[i] = max(best[i],best[i+1]); } long long ans = -1; for (long long i = 1;i <= n;i ++){ ans = max(ans,best[i] - a[i-1].second + a[i].first); } cout<<ans<<'\n'; return 0; }