#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
long long n;
cin >> n;
auto ab = new pair<long long, long long>[n];
for (long long i = 0; i < n; i++)
{
cin >> ab[i].first >> ab[i].second;
}
std::sort(ab, ab + n);
long long amin = 0;
long long s = 0;
long long m = 0;
for (long long i = 0; i < n; i++)
{
s += ab[i].second;
//while (amin < i && (s - (ab[i].first - ab[amin].first) < s - ab[amin].second - (ab[i].first - ab[amin + 1].first)))
while (amin < i && ( ab[amin].first < - ab[amin].second + ab[amin + 1].first))
{
s -= ab[amin].second;
amin++;
}
if (ab[i].second > s - (ab[i].first - ab[amin].first))
{
s = ab[i].second;
amin = i;
}
if (s - (ab[i].first - ab[amin].first) > m)
{
m = s - (ab[i].first - ab[amin].first);
}
}
cout << m << '\n';
}
