// JOI 2018
#include <bits/stdc++.h>
#include <climits>
using namespace std;
#define int int64_t
struct art {
int si;
int val;
bool operator<(const art& other) const {
if(si == other.si)
return val > other.val;
return si < other.si;
}
};
void sol()
{
int n;
cin >> n;
vector<art> a(n);
for(int i = 0; i < n; i++) {
cin >> a[i].si >> a[i].val;
}
sort(a.begin(), a.end());
int max_score = INT_MIN;
for(int i = 0; i < n; i++) {
int tot_val = 0;
int min_si = a[i].si;
for(int j = i; j < n; j++) {
int max_si = a[j].si;
tot_val += a[j].val;
int score = tot_val - (max_si - min_si);
max_score = max(max_score, score);
}
}
cout << max_score << '\n';
}
int32_t main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
sol();
return 0;
}
