#include <iostream>
#include <algorithm>

#define x first
#define y second

using namespace std;
typedef pair<int, int> PII;

const int N = 200010;
PII a[N];
int n, d;

int  main()
{
    scanf("%d%d", &n, &d);

    for (int i = 0; i < n; i++) scanf("%d%d", &a[i].x, &a[i].y);

    sort(a, a + n);

    int maxv = 0;
    int res = 0;
    for (int i = -1, j = 1; j < n; j++)
    {
        while (j > i + 1 && a[j].x - a[i + 1].x >= d) 
        {
            maxv = max(maxv, a[i + 1].y);
            i++;
        }

        if (i != -1 && a[j].x - a[i].x >= d) res = max(res, a[j].y + maxv);
    }

    cout << res << endl;

    return 0;
}