#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
using namespace std;
typedef long long ll;

int n;
ll now;
ll cost;
double w[100][100];
double p[100];
double ans;

int main()
{
    freopen("tvshow.in", "r", stdin);
    freopen("tvshow.out", "w", stdout);

    scanf("%d%I64d\n", &n, &cost);
    for (int i = 0; i < n; i++)
    {
        scanf("%lf", &p[i]);
        p[i] /= 100.;
    }
    for (int i = 0; i < n; i++)
    {
        w[i][i] = 1.;
        for (int j = i + 1; j <= n; j++)
            w[i][j] = w[i][j - 1] * p[j - 1];
    }
    ans = 100.;
    for (int i = 1; i <= n; i++)
        ans = max(ans, w[0][i] * (double)(100LL << (ll)i));
    now = 50LL;

    for (int i = 0; i < n; i++)
    {
        now = now << 1LL;
        if (now <= cost)
            continue;
        ll tmp_now = now - cost;
        double r = w[0][i] * (double)tmp_now;
        double tans = 0.;
        for (int j = i; j <= n; j++)
        {
            double rr = r * (1. - p[j]);
            double tt = 0.;
            for (int k = j + 1; k <= n; k++)
            {
                tt = max(rr, tt);
                if (k < n)
                    rr = rr * p[k] * 2.;
            }
            tans += tt;
            if (j < n)
                r = r * p[j] * 2.;
        }
        tans += r;
        ans = max(ans, tans);
    }

    printf("%.10lf\n", ans);
    return 0;
}