#include <iostream>
#include <vector>
using namespace std;

struct SegmentTree {
    struct Node {
        int value;
        Node* left;
        Node* right;

        Node(int v, Node* l, Node* r) {
            this->value = v;
            this->left = l;
            this->right = r;
        }

        Node() {
            this->value = 0;
            this->left = NULL;
            this->right = NULL;
        }
    };

    Node root;

    int power_2_over(int x) {
         x--;
         for (int p=1; p<32; p<<=1) x |= (x >> p);
         return ++x;
    }

    SegmentTree(vector<int> array, size_t size) {
        size = power_2_over(size);
        vector<Node> prev_nodes (size);
        for (size_t i = 0; i < size; i++)
            prev_nodes[i].value = array[i];
        while (prev_nodes.size() > 1) {
            vector<Node> nodes (prev_nodes.size() / 2);
            size_t j = 0;
            for (size_t i = 0; i < prev_nodes.size(); i += 2) {
                nodes[j].value = prev_nodes[i].value + prev_nodes[i + 1].value;
                nodes[j].left = &prev_nodes[i];
                nodes[j].right = &prev_nodes[i + 1];
                j++;
            }
            prev_nodes = nodes;
        }
        root = prev_nodes[0];
    }

};


int main()
{
    int n;
    cin >> n;
    vector<int> a(n);
    for (size_t i = 0; i < n; i++)
    SegmentTree t(a, n);
    cout << t.root.value;
    return 0;
}