#include <bits/stdc++.h>
using namespace std;

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second
#define FILL(a, b) memset(a, b, sizeof(a))

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

typedef long double db;

long double solve(int n, int k, int x, vector<LL> a){
	LL sum = 0;
	FOR(i, 0, n){
		a[i] -= x;
		sum += a[i];
	}
	
	if(sum < 0){
		FOR(i, 0, n)
			a[i] *= -1;
		sum *= -1;
	}
	
	sort(ALL(a));
	LL mn = sum;
	if(k == 0)
		mn = sum;
	if(k == 1){
		FOR(i, 0, n)
			mn = min(mn, abs(sum - a[i]));
	}
	if(k == 2){
		FOR(i, 0, n)
			FOR(j, i + 1, n)
				mn = min(mn, abs(sum - a[i] - a[j]));
	}
	if(k == 3){
		FOR(i, 0, n)
			FOR(j, i + 1, n)
				FOR(z, j + 1, n)
					mn = min(mn, abs(sum - a[i] - a[j] - a[z]));
	}
	if(k == 4){
		FOR(i, 0, n - 3)
			FOR(j, i + 1, n - 2){
				int z = j + 1;
				
				LL cur = a[i] + a[j] + a[z];
				
				int pos = n - 1;
				
				while(z < n){
					
					while(pos > z && a[pos] + cur > sum)
						pos--;
					
					if(pos + 1 != n)		
						mn = min(mn, a[pos + 1] + cur - sum);
					
					if(pos == z)
						break;
					
					mn = min(mn, sum - a[pos] - cur);				
					z++;
				}
			}
	}
	
	
	
	
	return 1.0 * mn / (n - k);
} 




int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n, k, x;
	cin >> n >> k >> x;
	
	vector<LL> a(n);
	FOR(i, 0, n)
		cin >> a[i];

	db ans = solve(n, 0, x, a);
	FOR(i, 1, k + 1)
		ans = min(ans, solve(n, i, x, a));
		
	cout << fixed << setprecision(10) << ans << endl;

	
	
	
	return 0;
}