#include <bits/stdc++.h>
using namespace std;
int main () {
	int N, H;
	cin >> N >> H;
	std::vector<int> A(H + 1, 0);
	for (int i = 0; i < N; i ++) {
		int a, b;
		cin >> a >> b;
		A[a] ++;
		A[++b] --;
	}
	int ans = 0;
	int s = 0;
	for (auto& a : A) {
		s += a;
		ans = max(ans, s);
	}
	cout << ans << endl;
}