#include<iostream>
#include<vector>
using namespace std;

int main(){
    int n, m;
    cin >> n >> m;
    vector<bool> w(m, 0);
    for(int i = 0; i < n; i++){
        int l, r;
        cin >> l >> r;
        bool ok = true;
        for(int j = l; j <= r; j++) ok &= !w[j];
        if(ok){
            for(int j = l; j <= r; j++) w[j] = true;
            continue;
        }
        ok = true;
        for(int j = l; j <= r; j++) ok &= !w[m-1-j];
        if(ok){
            for(int j = l; j <= r; j++) w[m-1-j] = true;
            continue;
        }
        cout << "NO" << endl;
        return 0;
    }
    cout << "YES" << endl;
    return 0;
}