#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <deque>
#include <numeric>
#include <utility>
#include <sstream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cctype>
#include <cstring>
#include <stack>
#include <assert.h>
using namespace std;

#define IT(c) typeof((c).begin())

#define For(i, a, b) for(int (i) =  int(a); i < int(b); ++i)
#define rep(x, n) For(x,0,n)
#define foreach(i, c) for(IT(c) i = (c).begin(); i != (c).end(); ++i)

#define sz(a) int((a).size())
#define pb push_back
#define mp make_pair
#define F first
#define S second

#define setmax(a,b) a = max(a,b)

typedef vector<int> Vi;
typedef vector<vector<int> > Vvi;
typedef vector<string> Vs;
typedef pair<int, int> Pi;


double DP[5005][1005][2];
int main(){
while(1){
	int n; cin>>n;
	if(n==0) break;
	int c, t; cin>>c>>t;
	rep(i, n+1) rep(k,t+1) rep(j,2) DP[i][k][j] = -1e100;
	DP[0][t][0] = log10(c);
	rep(i,n){
		double v; cin>>v;
		v = log10(v);
		rep(j, t+1){
			setmax(DP[i+1][j][0], DP[i][j][0]);  
			if(j > 0){ setmax(DP[i+1][j-1][0], DP[i][j][1] + v);
			}
			setmax(DP[i+1][j][1], DP[i][j][1]);
			if(j > 0){ setmax(DP[i+1][j-1][1], DP[i][j][0] - v);
			}
		}
	}
	double res = 0;
	rep(i, t+1) res = max(res, DP[n][i][0]);
	cout<<fixed<<setprecision(10)<<res<<endl;
}	
}