#include <iostream>
#include <fstream>
#include <vector>
#include <set>
#include <queue>
#include <cmath>
#include <map>
#include <algorithm>
#include <numeric>
#include <stack>
#include <cstring>
#include <bitset>
#include <climits>
#include <valarray>
#include <list>
#define int long long
#define inf 1000000000
#define endl '\n'
#define mod 1000000007
using namespace std;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n; cin >> n;
pair<int,int> ar[n];
for (int i = 0; i < n; i++) cin >> ar[i].first >> ar[i].second;
int mx = 0;
sort(ar, ar+n);
for (int i = 1; i < n; i++) ar[i].second += ar[i-1].second;
for (int i = 0; i < n; i++){
for (int j = i; j < n; j++){
int cur;
if (i == 0) cur = ar[j].second;
else cur = ar[j].second-ar[i-1].second;
mx = max(mx, cur-(ar[j].first-ar[i].first));
}
}
cout << mx << endl;
}
