#include<bits/stdc++.h> #define endl "\n" using namespace std ; typedef long long ll; typedef long double ld ; #define pb push_back #define pp pop_back const int N=1e6+9; const ll inf=1e18 ; const ll mod = 1e9+9 ; #define fast ios::sync_with_stdio(0);cin.tie(0);cout.tie(0); ll n ,a[N] , x, y,k,t[N],pre[N]; vector<ll>vec; void solve(){ cin>>n; vector<pair<ll,ll>>vec(n); for(int i=0;i<n;i++){ cin>>vec[i].first>>vec[i].second; } sort(vec.begin(),vec.end()); pre[0]=vec[0].second; for(int i=1;i<n;i++){ pre[i]=pre[i-1]+vec[i].second; } ll ans=-10,mx=-10; for(int i=0;i<n;i++){ if(i>0){ ans=max(pre[i]-vec[i].first+mx,ans); } mx = max(mx,vec[i].first-pre[i]); } cout<<ans; } int main(){ fast; ll t=1;//cin>>t; while(t--)solve(); return 0; }