#include "bits/stdc++.h"
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define ll long long
#define pb push_back
#define in insert
#define F first
#define S second
#define vll vector<ll>
#define all(v) v.begin(),v.end()
#define endl '\n'
#define pii pair<ll,ll>
using namespace std;
const ll INF = 1e18, mod = 1e9 + 7, N = 2e5 + 5;
ll gcd(ll a, ll b){
if(b == 0){
return a;
}
return gcd(b, a%b);
}
ll lcm(ll a, ll b){
return (a / gcd(a,b)) * b;
}
void solve(){
ll n,m;
cin >> n;
vector<pii>v;
v.pb({0, 0});
ll a,b;
for(int i = 0; i < n; i++){
cin >> a >> b;
v.pb({a,b});
}
vector<ll>pre(n + 1, 0);
sort(all(v));
pre[1] = v[1].S;
ll maxi = 0;
ll mini = v[1].F, maximum = v[1].F;
for(int i = 2; i <= n; i++){
mini= min(mini, v[i].F);
maximum = max(maximum, v[i].F);
pre[i] = pre[i - 1] + v[i].S;
maxi = max(maxi, pre[i] - (maximum - mini));
}
cout << maxi << endl;
/*ll maxi = 0;
for(int i = 1; i <= n; i++){
for(int j = i; j <= n; j++){
maxi = max(maxi, pre[j] - pre[i - 1] - (v[j].F - v[i].F));
}
}
cout << maxi << endl;*/
}
int main() {
fast;
ll t = 1;
// cin >> t;
while(t--){
solve();
}
return 0;
}
