#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i = 0; i < (int)n; i++)
using ll = long long int;

int main() {
  int n, h;
  cin >> n >> h;
  vector<int> v(h+1, 0);
  rep(i, n) {
    int a, b;
    cin >> a >> b;
    v[a]++;
    v[b+1]--;
  }
  int m = 0;
  int ma = 0;
  rep(i, h+1) {
    m += v[i];
    ma = max(m, ma);
  }
  cout << ma << endl;
  return 0;
}