#include<bits/stdc++.h> #define ll long long #define ii pair<long long, long long> using namespace std; const int MAXN = 5*1e5 + 5; ll n,res=0,dis=1e9; ll a[MAXN]; ii p[MAXN]; int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cin>>n; for(int i = 1;i<=n;i++){ cin>>p[i].first>>p[i].second; } sort(p+1,p+n+1); for(int i = 1;i<=n;i++){ p[i].second = p[i].second + p[i-1].second; } for(int i = 1;i<=n;i++){ dis = min(dis,p[i-1].second - p[i].first); res = max(res,p[i].second - p[i].first - dis); } cout<<res; return 0; }