#include <bits/stdc++.h>
#define f first
#define s second

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

const int MAXN = 211111;
const double eps = 0.5;
vector <pii> a;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, t;
    cin >> n >> t;
    a.resize(n);
    vector <int> tmp(n);
    for(int i = 0; i < n; i++){
        int l, r;
        cin >> l >> r;
        a[i] = {l, r};
        tmp[i] = l;
    }
    sort(a.begin(), a.end());
    sort(tmp.begin(), tmp.end());
    int ans = 0;
    for(int i = 0; i < n; i++){
        double cur_l = a[i].f - eps, cur_r = a[i].f + t - eps;
        int cur_upper, cur_lower;
        cur_upper = cur_lower = 0;
        for(int j = i; j < n; j++)
            if(a[j].f > cur_l && a[j].s < cur_r)cur_lower++;
        int pos = lower_bound(tmp.begin(), tmp.end(), a[i].f) - tmp.begin();
        for(int j = 0; j < pos; j++)
            if(a[j].s > cur_r)cur_upper++;
        ans = max(ans, cur_lower - cur_upper);
    }
    cout << ans << '\n';
    return 0;
}