#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>

// WA: Only tries integer framerates
int main(){
    int n, m;
    std::cin >> n >> m;
    std::vector<float> xs;
    int x;
    for (int i = 0; i < n; i++)
    {
        std::cin >> x;
        xs.push_back(x);
    }
    float optt = 1000000000.0f;
    for (int f = 1; f <= m; f++)
    {
        float t = 0;
        for (int i = 0; i < n; i++)
        {
            int x = xs[i];
            t += (f * x) / 1000 + ((f * x) % 1000 == 0 ? 0 : 1);
        }
        t = (float)t / f;
        if (t < optt) optt = t;
    }

    std::cout << std::setprecision(10) << optt << std::endl;

}