#include <bits/stdc++.h>
#define sts(v) stable_sort(v.BE, v.E)
#define Rsts(v) stable_sort(v.rBE, v.rE)
#define rev(v) reverse(v.BE, v.E)
#define BE begin()
#define rBE rbegin()
#define E end()
#define rE rend()
#define pb push_back
#define ppb pop_back()
#define pf push_front
#define ppf pop_front()
#define F first
#define S second
using namespace std;
using ll = long long;
struct datos{
ll ans, maxi, mini, suma;
};
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n; cin >> n;
vector<pair<ll, ll>> v(n + 1);
for(int i = 1; i <= n; i++){
ll a, b; cin >> a >> b;
v[i] = {a, b};
}
sts(v);
vector<datos> ans(n + 1);
ll ANS = 0;
for(int i = 1; i <= n; i++){
// F -> size, S -> val
ans[i] = {
v[i].S,
v[i].F,
v[i].F,
v[i].S
};
for(int j = 1; j < i; j++){
ll maxi = max(ans[j].maxi, v[i].F), mini = min(ans[j].mini, v[i].F),
suma = ans[j].suma + v[i].S, res = suma - (maxi - mini);
if(res > ans[i].ans)
ans[i] = {
res,
maxi,
mini,
suma
};
ANS = max(ANS, ans[i].ans);
}
// cout << ans[i].ans << '\n';
}
cout << ANS << '\n';
return 0;
}
