#define _USE_MATH_DEFINES
 
#include <iostream>
#include <iomanip>
#include <sstream>
 
#include <algorithm>
#include <cmath>
 
#include <string>
//#include <array>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>
 
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
 
#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(16);//
	
	int N,M;
	cin>>N>>M;
	int L,R;
	bool col[4000];
	rep(i,M) col[i] = false;

	bool ret = false;
	rep(i,N){
		cin>>L>>R;
		ret = true;
		//そのまま
		for(int j = L; j <= R; ++j){
			if( col[j] != false ){
				ret = false;
				break;
			}
		}
		if( ret == true ){
			for(int j = L; j <= R; ++j){
				col[j] = true;//塗る
			}
		}
		else if( ret == false ){//反転チェック
			ret = true;
			for(int j = L; j <= R; ++j){
				if( col[M-1-j] != false ){
					ret = false;
					break;
				}
			}
			if( ret == true ){
				for(int j = L; j <= R; ++j){
					col[M-1-j] = true;
				}
			}
		}
		
		if( ret == false ){
			P("NO");
			return 0;
		}
	}
	P("YES");
	return 0;
}