#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, a, b) for (int i = a; i < (b); ++i)

int main()
{
    int n, h;
    cin >> n >> h;
    vector<int> imos(h + 2);
    rep(_, 0, n)
    {
        int l, r;
        cin >> l >> r;
        imos[l]++;
        imos[r + 1]--;
    }
    int ans = 0, tmp = 0;
    rep(i, 0, h + 2)
    {
        tmp += imos[i];
        ans = max(ans, tmp);
    }
    cout << ans << endl;
}