#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int n, m;
    cin >> n >> m;

    vector< vector<int> > memo(m);
    for (int i = 0; i < n; i++) {
        int l, r;
        cin >> l >> r;

        int tmp = m - 1 - r;
        if (tmp < l) {
            r = m - 1 - l;
            l = tmp;
        }

        memo[l].push_back(r);
    }

    vector<int> used(m, false);
    for (int i = 0; i < m; ++i) {
        if (memo[i].empty()) continue;

        int hoge = memo[i].size() + used[i];
        if (hoge > 2) {
            cout << "NO\n";
            return 0;
        }

        if (hoge == 2 && !used[i]) {
            if (memo[i][0] > memo[i][1]) swap(memo[i][0], memo[i][1]);
            int l = i;
            int r = memo[i][1];
            int l2 = i;
            int r2 = memo[i][0];
            for (int j = i; j <= memo[i][1]; j++) {
                if (used[j]) {
                    if (j <= memo[i][0]) {
                        cout << "NO\n";
                        return 0;
                    } else if (j <= memo[i][1]) {
                        swap(r, r2);
                        break;
                    }
                }
            }

            {
                int tmp = m - 1 - r2;
                r2 = m - 1 - l2;
                l2 = tmp;
            }

            for (int j = l; j <= r; j++) {
                if (used[j]) {
                    cout << "NO\n";
                    return 0;
                }
                used[j] = true;
            }

            for (int j = l2; j <= r2; j++) {
                if (used[j]) {
                    cout << "NO\n";
                    return 0;
                }
                used[j] = true;
            }            
        } else {
            int l = i;
            int r = memo[i][0];
            if (used[i]) {
                int tmp = m - 1 - r;
                r = m - 1 - l;
                l = tmp;
            }

            for (int j = l; j <= r; j++) {
                if (used[j]) {
                    cout << "NO\n";
                    return 0;
                }
                used[j] = true;
            }
        }
    }
    cout << "YES\n";

    return 0;
}