#include <bits/stdc++.h>
#include <atcoder/scc>
using namespace std;
using ll = long long;
const int mod = 998244353;

int N, M;
bool S[2010][4010];
int main(void){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    cin >> N >> M;
    for(int i = 0;i < N;i++){
        int l, r; cin >> l >> r;
        for(int j = l;j <= r;j++){
            S[i][j] = true;
        }
    }
    atcoder::scc_graph G(2 * N);
    for(int j = 0;j < (M + 1) / 2;j++){
        int cnt = 0;
        vector<int> hit;
        for(int i = 0;i < N;i++){
            cnt += S[i][j] + S[i][M - 1 - j];
            if(S[i][j] || S[i][M - 1 - j]){
                hit.push_back(i);
            }
        }
        if(cnt > 2){
            cout << "NO" << endl;
            return 0;
        }
        if(cnt == 2 && hit.size() == 2){
            if(S[hit[0]][j] ^ S[hit[1]][j]){
                G.add_edge(hit[0], hit[1]);
                G.add_edge(hit[1], hit[0]);
            }else{
                G.add_edge(hit[0], hit[1] + N);
                G.add_edge(hit[1], hit[0] + N);
            }
        }
    }
    vector<vector<int>> res = G.scc();
    for(auto vec : res){
        bool seen[2010] = {};
        for(int v : vec){
            if(v > N)v -= N;
            if(seen[v]){
                cout << "NO" << endl;
                return 0;
            }
            seen[v] = true;
        }
    }
    cout << "YES" << endl;
    return 0;
}