#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
using namespace std;
bool Judge(int a[],int n)
{
    int i;
    for (i = 1; i < ceil(n / 2);i++)
    if ((a[i]>a[i * 2] && 2 * i<n) || (a[i]>a[i * 2 + 1] && (2 * i + 1) < n))
        return false;
    return true;
}
int main()
{
    int i, n, a[100];
    cin >> n;
    for(i = 1; i <= n; i++)
        cin >> a[i];
    if (Judge(a, n))
        cout << "Yes";
    else
        cout << "No";
}