#include <bits/stdc++.h>
using namespace std;
// #pragma GCC optimize("Ofast")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
// #pragma GCC optimize("unroll-loops")
#define ll long long
#define int128 __int128_t
#define pii pair<int, int>
#define int long long
#define pb push_back
#define F first
#define S second
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).begin(), (v).end()
#define MOD 1000000007
#define INF (ll)1e18
#define RINF (ll) - 1e18
void cinv(vector<int> &a, int n){for (int i = 0; i < n; i++){cin >> a[i];}}
void coutv(vector<int> &a, int n){for (int i = 0; i < n; i++){cout << a[i] << " ";}}
void solve()
{
int n;
cin>>n;
vector<pair<int,int>>a;
for(int i = 0;i<n;i++){
int x,y;
cin>>x>>y;
a.push_back({x,y});
}
sort(a.rbegin(),a.rend());
int d = 0;
for(int i = 0;i<n;i++){
int q = -1e18;
int f = 1e18;
int y = 0;
for(int j = i;j<n;j++){
y+=a[j].S;
f = min(f,a[j].F);
q = max(q,a[j].F);
d = max(d,y-(q-f));
}
}
cout<<d<<endl;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int t = 1;
// cin >> t;
while (t--)
{
solve();
}
}
