inline int hsh(vi vec){
    int ans = 0;
    for(int v: vec)
        ans = ans * 50 + v;
    return ans;
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    while(cin >> n){
        for(int i = 0; i < n; ++i)
            cin >> m[i];
        cin >> t;

        bool oao = false;
        for(int i = 0; i < n; ++i)
            if(m[i] >= t) oao = true;
        if(!oao){
            cout << -1 << '\n';
            continue;
        }

        int g = 0;
        for(int i = 0; i < n; ++i)
            g = gcd(g, m[i]);
        if(t % g){
            cout << -1 << '\n';
            continue;
        }

        bool ans = false;

        queue<piv> q;
        unordered_set<int> vis;
        q.push({0, vi(n,0)});
        vis.insert(hsh(vi(n,0)));

        while(!ans and !q.empty()){
            int stp = q.front().ff;
            vi jiz = q.front().ss;
            q.pop();

            // cout << "Step: " << stp << '\n';
            // for(int i = 0; i < n; ++i)
            //  cout << jiz[i] << ' ';

            for(int i = 0; i < n; ++i)
                if(jiz[i] == t){
                    ans = true;
                    cout << stp << '\n';
                    break;
                }

            // empty one cup
            for(int i = 0; i < n; ++i){
                vi eek = jiz;
                eek[i] = 0;
                if(vis.count(hsh(eek)) == 0)
                    vis.insert(hsh(eek)), q.push({stp + 1, eek});
            }

            // fill one cup
            for(int i = 0; i < n; ++i){
                vi eek = jiz;
                eek[i] = m[i];
                if(vis.count(hsh(eek)) == 0)
                    vis.insert(hsh(eek)), q.push({stp + 1, eek});
            }

            // pour from i to j
            for(int i = 0; i < n; ++i){
                for(int j = 0; j < n; ++j){
                    if(i == j) continue;
                    vi eek = jiz;
                    // fill up j
                    if(m[j] - eek[j] <= eek[i]){
                        eek[i] -= m[j] - eek[j];
                        eek[j] = m[j];
                    }
                    // emtpy i
                    else {
                        eek[j] += eek[i];
                        eek[i] = 0;
                    }
                    if(vis.count(hsh(eek)) == 0)
                        vis.insert(hsh(eek)), q.push({stp + 1, eek});
                }
            }
        }
        if(!ans) cout << -1 << '\n';
    }
    return 0;
}