#include <cstdio>

#include <cstdlib>

#include <algorithm>

#include <functional>

#include <queue>

using namespace std;

#define MAX_COLOR_NUM 20

int color_num;

int gray_vol;

int color_vol[MAX_COLOR_NUM];

int ans;

void input()

{

    int max_vol = ;

    for (int i = ; i < color_num; i++)

    {

        scanf("%d", &color_vol[i]);

        max_vol = max(color_vol[i], max_vol);

    }

    scanf("%d", &gray_vol);

    ans = (max_vol + ) / ;

}

void produce_gray()

{

    priority_queue<int> pq;

    for (int i = ; i < color_num; i++)

        if (color_vol[i] != )

        {

            pq.push(color_vol[i]);

            color_vol[i] = ;

        }

    while (pq.size() >= )

    {

        int a = pq.top();

        pq.pop();

        int b = pq.top();

        pq.pop();

        int c = pq.top();

        pq.pop();

        a--;

        b--;

        c--;

        gray_vol--;

        if (a)

            pq.push(a);

        if (b)

            pq.push(b);

        if (c)

            pq.push(c);

    }

    int i = ;

    while (!pq.empty())

    {

        color_vol[i] = pq.top();

        pq.pop();

        i++;

    }

}

void work()

{

    for (int i = ; i < color_num; i++)

        color_vol[i] = ans *  - color_vol[i];

    while ()

    {

        produce_gray();

        if (gray_vol <= )

            break;

        ans++;

        for (int i = ; i < color_num; i++)

            color_vol[i] += ;

    }

    printf("%d\n", ans);

}

int main()

{

    while (scanf("%d", &color_num), color_num)

    {

        input();

        work();

    }

    return ;

}