#include <bits/stdc++.h>
using namespace std;



int seven;

int recursion(int arr[], int pos, int n)
{
    if (pos == n) return 0;

    if (pos == 0) seven = 1;
    else seven *= 7;

    return (seven * arr[pos]) + recursion(arr, pos + 1, n);
}

int main()
{
    int n = 6;
    int arr[6] = {2, 4, 5, -1, 4, 6};
    int ans = recursion(arr, 0, n);
    cout << ans << '\n';

    return 0;
}