#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;

    int a[1005];

    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }

    for (int i = 1; i <= n; i++) {
        if (2 * i <= n && a[i] > a[2 * i]) {
            cout << "No" << endl;
            return 0;
        }
        if (2 * i + 1 <= n && a[i] > a[2 * i + 1]) {
            cout << "No" << endl;
            return 0;
        }
    }

    cout << "Yes" << endl;
    return 0;
}