/* -*- coding: utf-8 -*-
 *
 * 3039.cc:  No.3039 驟堺ｿ｡閠・- yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_H = 1000000;

/* typedef */

/* global variables */

int cs[MAX_H + 1];

/* subroutines */

/* main */

int main() {
  int n, h;
  scanf("%d%d", &n, &h);

  for (int i = 0; i < n; i++) {
    int ai, bi;
    scanf("%d%d", &ai, &bi);
    cs[ai]++, cs[bi + 1]--;
  }

  for (int i = 0; i < h; i++) cs[i + 1] += cs[i];
  int maxd = *max_element(cs, cs + h);

  printf("%d\n", maxd);

  return 0;
}