#include <bits/stdc++.h>

using namespace std;

int main() {
    int n, n1, n2, n3, p1, p2, p3, t1, t2, t3, total;
    cin >> n >> n1 >> p1 >> n2 >> p2 >> n3 >> p3;
    t1 = ceil(1.0 * n / n1) * p1;
    t2 = ceil(1.0 * n / n2) * p2;
    t3 = ceil(1.0 * n / n3) * p3;
    total = t1;
    if (t2 < total) total = t2;
    if (t3 < total) total = t3;
    cout << total << endl;
    return 0;
}