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

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

using ll=long long;

int main(){
	int N,H;cin>>N>>H;
	
	vector<int> sm(H+10);
	while(N--){
		int a,b;cin>>a>>b;
		sm[a]++;
		sm[b+1]--;
	}
	for(int i=0;i<H+5;i++)sm[i+1]+=sm[i];

	cout<<*max_element(sm.begin(),sm.end())<<endl;
}