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

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<vvvi> vvvvi;
typedef vector<ii> vii;

#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(), (v).end()

ll get_close(const vi& A, const vi& B, ll t) {
	ll i = 0, j = B.size()-1;
	ll best = A[0]+B[0];
	while (i < A.size() && j >= 0) {
		ll v = A[i] + B[j];
		if (abs(v-t) < abs(best-t)) {
			best = v;
		}
		if (v < t) {
			i++;
		} else {
			j--;
		}
	}
	return best;
}

ld best(ld r1, ld r2, ld t) {
	if (abs(r1-t) < abs(r2-t)) {
		return r1;
	} else {
		return r2;
	}
}

const ll INF = 4'000'000'000'000'000'000;

void run() {
	ll n, k, t;
	cin >> n >> k >> t;
	vi A(n);
	ll s = 0;
	for (ll i = 0; i < n; i++) {
		cin >> A[i];
		s += A[i];
	}
	sort(all(A));
	set<ll> T1{-INF,INF};
	set<ll> T2{-INF,INF};
	ld res = ((ld) s)/n;
	for (ll i = 0; i < n; i++) {
		if (k >= 1) res = best(res, ((ld)s-A[i])/(n-1),t);
		for (ll j = i+1; j < n; j++) {
			if (k >= 2) res = best(res, ((ld)s-A[i]-A[j])/(n-2),t);
			auto p11 = T1.lower_bound(s-A[i]-A[j]-t*(n-3));
			auto p12 = T1.lower_bound(s-A[i]-A[j]-t*(n-3)); p12--;
			auto p21 = T2.lower_bound(s-A[i]-A[j]-t*(n-4));
			auto p22 = T2.lower_bound(s-A[i]-A[j]-t*(n-4)); p22--;
			if (k >= 3) res = best(res, ((ld)s-A[i]-A[j]-*p11)/(n-3),t);
			if (k >= 3) res = best(res, ((ld)s-A[i]-A[j]-*p12)/(n-3),t);
			if (k >= 4) res = best(res, ((ld)s-A[i]-A[j]-*p21)/(n-4),t);
			if (k >= 4) res = best(res, ((ld)s-A[i]-A[j]-*p22)/(n-4),t);
		}
		T1.insert(A[i]);
		for (ll j = 0; j < i; j++) {
			T2.insert(A[i]+A[j]);
		}
	}
	cout << abs(res - t) << endl;
}

signed main() {
    ios_base::sync_with_stdio(false); cin.tie(0);
	cout << fixed << setprecision(20);
    run();
    return 0;
}