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

void solve(){
	ll N,H;cin>>N>>H;
	vector<int> P(H+1,0),Q(H+1,0);
	for(int i=0;i<N;i++){
		ll A,B;
		cin>>A>>B;
		P[A]++;
		Q[B]++;
	}
	ll bn=0,an=0;
	for(int t=0;t<=H;t++){
		bn+=P[t];
		an=max(an,bn);
		bn-=Q[t];
	}
	cout<<an<<endl;

}

int main(){
	
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	int T=1;
	// cin>>T;
	while(T--)solve();
}