#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include<bits/stdc++.h>
using namespace __gnu_pbds;
using namespace std;
typedef long long ll;
#define fr first
#define sc second
#define mk make_pair
#define pb push_back
#define pob pop_back
#define pf push_front
#define pof pop_front
#define int long long
#define pii pair<int,int>
#define piii pair<int,pii>
#define all(s) s.begin(), s.end()
#define allr(s) s.rbegin(), s.rend()
#define NeedForSpeed ios::sync_with_stdio(0), cin.tie(0)
#define ordered_set tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>
const int N = 5e5 + 12;
int n, m, k, a, b, c, d, pref[N];
vector<pii>v;
void solve(){
cin>>n;
v.pb({0, 0});
for(int i=0; i<n; i++){
int x, y;
cin>>x>>y;
v.pb({x, y});
}sort(all(v));
for(int i=1; i<=n; i++){
pref[i] = pref[i-1] + v[i].sc;
}
int l = 0, res = 0, ans = 0;
for(int r=1; r<=n; r++){
ans = max(ans, pref[r] - pref[l-1] - v[r].fr + v[l].fr);
while(l <= r && ans < pref[r] - pref[l] - v[r].fr + v[l+1].fr){
l++;
ans = max(ans, pref[r] - pref[l-1] - v[r].fr + v[l].fr);
}
//cout<<l<<" "<<r<<endl;
res = max(res, ans);
}
cout<<res<<"\n";
}
main(){
NeedForSpeed;
int T = 1;
// cin >> T;
while(T--){
solve();
}
return 0;
}
