#include <iostream>
#include <fstream>

using namespace std;

size_t N;
size_t K;
size_t len;
size_t ** dp;
size_t * arr;

void update(size_t i) {
    size_t left = 2 * i + 1;
    size_t right = 2 * i + 2;
    dp[i][0] = arr[i];
    size_t max = 0;

    for (size_t j = 1; j <= K; ++j) {
        for (size_t k = 0; k <= j; ++k) {
            size_t k_rev = j - k;
            size_t left_sum = 0;
            size_t right_sum = 0;

            if (k > 0) {
                left_sum = dp[left][k - 1];
            }
            if (k_rev > 0) {
                right_sum = dp[right][k_rev - 1];
            }

            size_t sum = left_sum + right_sum;
            if (sum > max) {
                max = sum;
            }
        }
        dp[i][j] = max + arr[i];
    }
}


int main() {

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> N;
    len = pow(2, N) - 1;
    arr = new size_t[len];

    for (size_t i = 0; i < len; ++i) {
        cin >> arr[i];
    }

    cin >> K;

    dp = new size_t*[len];
    dp[0] = new size_t[len * (K + 1)];

    for (size_t i = 1; i < len; ++i) {
        dp[i] = dp[i - 1] + (K + 1);
    }

    for (size_t i = 0; i < len; ++i) {
        for (size_t j = 0; j <= K; ++j) {
            dp[i][j] = 0;
        }
    }

    size_t last_lev = pow(2, N - 1);

    for (size_t i = 0; i < last_lev; ++i) {
        dp[len - 1 - i][0] = arr[len - 1 - i];
    }

    for (int i = len - last_lev - 1; i >= 0; --i) {
        update(i);
    }

    cout << dp[0][K];

}