#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> pii;
const int MAX_N = 4010;
int N,M;
int deg[MAX_N];
int main(){
  cin >> N >> M;

  for (int i = 0; i < N; i++){
    int l,r;
    cin >> l >> r;
    for (int k = l; k <= r; k++){
      deg[k]++;
    }
    l = (M - 1) - l;
    r = (M - 1) - r;
    for (int k = r; k <= l; k++){
      deg[k]++;
    }
  }
  bool ok = true;
  for (int i = 0; i < M; i++){
    ok &= deg[i] <= 2;
  }
  
  cout << (ok ? "YES" : "NO") << endl;
  return 0;
}