#include <iostream>
#include <fstream>

int main()
{
    int n;
    int a[1000024];

    std::ifstream f("twoton.in");
    std::ofstream g("twoton.out");

    f >> n;
    for (int i = 0; i < n; i++) {
        f >> a[i];
    }

    int total_size = 1;
    int current_level_size = 1;
    for (int i = 0; i < n - 1; i++) {
        if (a[i] >= a[n - 1]) {
            current_level_size *= 2;
            total_size += current_level_size;
        }
        else
            total_size += current_level_size;
    }

    g << total_size << std::endl;

    f.close();
    g.close();

    return 0;
}