#include <bits/stdc++.h>

#define pb push_back
#define mp make_pair
#define fr first
#define sc second
#define in insert

using namespace std;

vector <pair<int, int> > a;
int n, ans, k, t;

int main()
{
    cin >> n >> t;
    for (int i = 0; i < n; i++)
    {
        int x, y;
        cin >> x >> y;
        a.pb(mp(x, y));
    }
    sort(a.begin(), a.end());
    int tt = 0, tans = 0, k = 0;
    for (int i = 0; i < n; i++)
    {
        tt = a[i].fr;
        tans = 1;
        for (int j = k; j < i; j++)
            if (a[i].fr > a[j].sc)
                continue;
            else
            {
                k = j;
                break;
            }
        tans -= i - k;
        for (int j = i + 1; j < n; j++)
        {
            if (a[j].fr > tt + t)
                break;
            else if (a[j].sc <= tt + t)
                tans++;
            else if (a[j].sc > tt + t)
                tans--;
            ans = max(ans, tans);
        }
    }
    cout << ans;
    return 0;
}