#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int n, mxx = 0;
//int l = 0, r = 0;
cin>>n;
vector<pair<int,int>> vec(n);
vector<int> pfx(n+1,0);
for (int i = 0; i < n; ++i)
{
cin>>vec[i].first>>vec[i].second;
}
sort(vec.begin(),vec.end());
pfx[0] = vec[0].second;
for (int i = 1; i < n; ++i)
{
pfx[i] = pfx[i-1] + vec[i].second;
}
mxx = pfx[0];
for (int r = 1; r < n; ++r)
{
mxx = max(mxx, pfx[r] - (vec[r].first -vec[0].first));
}
for (int l = 1; l < n; ++l)
{
for (int r = l; r < n; ++r)
{
mxx = max(mxx, pfx[r] - pfx[l-1] - (vec[r].first -vec[l].first));
}
}
cout<<mxx<<endl;
return 0;
}
