#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000000
#define Inf64 1000000000000000001LL

int main(){
	int n,h;
	cin>>n>>h;
	vector<int> imos(h+5,0);
	rep(i,n){
		int a,b;
		cin>>a>>b;
		imos[a]++;
		imos[b+1]--;
	}
	rep(i,h+4)imos[i+1]+=imos[i];
	int ans = 0;
	rep(i,h+5)ans = max(ans,imos[i]);
	cout<<ans<<endl;
	
	return 0;
}