#include <iostream>
#include <algorithm>

using namespace std;

const int N = 200010;

typedef pair<int, int> PII;

PII a[N];

int main()
{
    int n, d;
    cin >> n >> d;
    for (int i = 1; i <= n; i ++ ) cin >> a[i].first >> a[i].second;

    sort(a + 1, a + 1 + n);

    int res = 0;

    for (int i = 1, j = 0, maxa = -1e9; i <= n; i ++ ) // maxa + a[].second必须 <= 0
    {
        while (j + 1 < i && a[i].first - a[j + 1].first >= d)
        {
            j ++ ;
            maxa = max(maxa, a[j].second);
        }
        res = max(res, a[i].second + maxa);
    }

    cout << res << endl;
    return 0;
}