.

#include <iostream>
#include <fstream>

using namespace std;

int a[1000], n;

void Citire()
{
    ifstream fin("fis.in");
    fin >> n;
    for(int i = 1; i <= n; i++)
        fin >> a[i];
    fin.close();
}

int Comp(int x)
{
    if((a[x-1] < a[x])&&(a[x] > a[x+1])) return 1;
    return 0;
}

int DeI(int st, int dr)
{
    if(st == dr)
    {
        if(st % 2 == 0) return Comp(st);
        return 1;
    }
    int m = (st+dr)/2;
    return DeI(st, m) && DeI(m+1, dr);
}

int main()
{
    Citire();
    cout << DeI(1, n);
    return 0;
}