#include <iostream>
using namespace std;

int main() {
    int n;
    int g[5] = {1,2,4,8,16};
    int arr[5];
    for (int i = 0;i < 5;i++) {
        cin >> arr[i];
    }
    
    cin >> n;
    int i = 4;
    int cnt = 0;
    while (true) {
        if (n < g[i] || arr[i] == 0){
            i -= 1;
            continue;
        }
        if (n == 0) {
            cout << cnt;
            return 0;
        }
        if (arr[0] == 0) break;
        n -= g[i];
        arr[i] -= 1;
        cnt++;
    }
    cout << "impossible";
    return 0;
}