#include <bits/stdc++.h>
#define left jkggh
#define right fbjflkg
#define ll long long
#define db long double
#define x first
#define y second
#define mp make_pair
#define pb push_back
#define all(a) a.begin(), a.end()

using namespace std;

struct Line{
    int l; int r;
    bool special;
};

bool cmp(Line &a, Line &b) {
    return (a.r < b.r);
}

short dp[8003][8003][2];

bool sat(Line &right, Line &left) {
    if (left.l < right.l && left.r > right.l && right.r > left.r) return true;
    return false;
}

int main(){
#ifdef LOCAL
    freopen("E_input.txt", "r", stdin);
    //freopen("E_output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, l;
    cin >> n >> l;

    l--;

    vector<Line> v;

    for (int i = 0; i < n; ++i) {
        int x, y;
        cin >> x >> y;
        v.push_back({x, y, false});
        v.push_back({y+1, y+l+1, true});
        v.push_back({x+1, x+l+1, true});
        v.push_back({x-l+1, x+1, true});
    }

    sort(v.begin(), v.end(), cmp);


    for (int i = 0; i < v.size(); ++i) {
        dp[i][0][v[i].special] = 1;

        int L = 0, R = v.size() + 1;
        while (R-L>1) {
            int M = (L+R)/2;
            if (v[M-1].r < v[i].l) L = M;
            else R = M;
        }
        int take = L;
        for (int j = 0; j < i; ++j) {
            if (!sat(v[i], v[j])) continue;
            for (int was = 0; was <= 1; ++was) {
                int T = was + v[i].special;
                if (T==2) continue;
                dp[i][j+1][T] = dp[j][take][was] + 1;
            }
        }
        for (int k = 0; k < 2; ++k) {
            for (int j = 1; j <= i; ++j) {
                dp[i][j][k] = max(dp[i][j][k], dp[i][j-1][k]);
            }
        }
    }

    short mx = 0;
    for (int i = 0; i < v.size(); ++i) {
        mx = max(mx, dp[i][i][0]);
        mx = max(mx, dp[i][i][1]);
    }
    cout << mx;
}