// 23 - 12 - 2023
#include<bits/stdc++.h>
using namespace std;
#define read() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define day() time_t now = time(0);char* x = ctime(&now);cerr<<"Right Now Is : "<<x<<"\n"
#define int long long
#define ii pair<int,int>
#define X first
#define Y second
const long long MAX = (int)5e5 + 5;
const long long INF = (int)1e9;
const long long MOD = (int)1e9 + 7;
int n;
ii a[MAX],b[MAX];
void solve(){
cin >> n;
for(int i = 1;i <= n;i++){
cin >> a[i].X >> a[i].Y;
}
sort(a + 1,a + 1 + n);
int mx = 0;
int sum = 0;
int res = 0;
for(int i = 1;i <= n;i++){
sum += a[i].Y;
mx = min(mx,sum - a[i].Y - a[i].X);
res = max(res,sum - a[i].X - mx);
}
cout << res << '\n';
}
signed main(){
read();
int t;
t = 1;
while(t--){
solve();
}
}
