#include<cstdio>
int fun(int a, int b, int c)
{
    int e = a / b;
    if (a % b)
        e++;
    e *= c;
    return e;
}
int main(void)
{
    int a, b, c, d[3], i = 3;
    scanf("d", &a);
    while (i)
    {
        scanf("%d%d", &b, &c);
        d[3 - i] = fun(a, b, c);
        i--;
    }
    for (int k = 1; k < 3; k++)
        if (d[k] < d[i])
            i = k;
    printf("%d", d[i]);
    return 0;
}