#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (ll)(n); i++)
#define all(a) (a).begin(), (a).end()
using ll = long long;
const int INF32 = 2e9;
const ll INF64 = 4e18;

int main() {
    int N, H;
    cin >> N >> H;
    vector<int> A(H,0), B(H,0),Aruiseki(H,0), Bruiseki(H,0);
    rep(i,N){
        int Ai, Bi;
        cin >> Ai >> Bi;
        A[Ai]++; B[Bi]++;
    }
    Aruiseki[0]=A[0];
    Bruiseki[0]=B[0];
    for(int i = 1; i < H; i++){
        Aruiseki[i]=Aruiseki[i-1]+A[i];
        Bruiseki[i]=Bruiseki[i-1]+B[i];
    }
    if(H==1){
        cout << A[0] << endl;
        return 0;
    }
    int ans = 0;
    for(int i = 1; i < H; i++) {
        ans = max(ans, Aruiseki[i]-Bruiseki[i-1]);
    }
    cout << ans << endl;
    return 0;
}