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#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4")
typedef long long LL;

double d[100019];

const double EPS = 0.000000000001;

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, t;
	cin>>n>>t;
	vector<double> v(n);
	for(auto &x : v)cin>>x;
	sort(v.begin(), v.end());
	reverse(v.begin(), v.end());
	
	int zero = 50005;
	d[zero] = 1;
	double res = 0;
	int p=zero;
	int k=zero;
	for(int i=0; i<n; i++){
		double r = 0;
		int pp = k+1;
		for(int j=p; j<=k; j+=2){
			double x = d[j] * v[i];
			d[j-1] += d[j] - x;
			d[j+1] += x;
			d[j]=0;
			if(d[j-1] > EPS) pp = min(pp, j-1);
		}
		int kk=p-1;
		p=pp;
		k++;
		int start = zero+t;
		if(start%2 != p%2)start++;
		for(int j=p; j<=k; j+=2){
			if(j>=start) r+=d[j];
			if(d[j] > EPS) kk = max(kk, j);
		}
		k=kk;
		res = max(res, r);
		if(abs(1.0 - res) < EPS) break;
	}
	cout << fixed << setprecision(9) << res << "\n";
	return 0;
}