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

void fast_io() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
}

int main() {
	fast_io();
	int n, k;
	cin >> n >> k;
	vector<pair<int, int>> xy(n);
	for (int i = 0; i < n; i++) {
		cin >> xy[i].first >> xy[i].second;
	}
	using ld = long double;
	vector<vector<ld>> dist(n, vector<ld>(n));
	vector<ld> dist_org(n);
	for (int i = 0; i < n; i++) {
		dist_org[i] = hypotl(xy[i].first, xy[i].second);
		for (int j = 0; j < n; j++) {
			dist[i][j] =
				hypotl(xy[i].first - xy[j].first, xy[i].second - xy[j].second);
		}
	}
	vector<vector<vector<ld>>> dp(1 << n,
								  vector<vector<ld>>(n, vector<ld>(k, 9e18)));
	for (int i = 0; i < n; i++) {
		dp[1 << i][i][k - 1] = dist_org[i];
	}
	for (int st = 0; st < (1 << n); st++) {
		for (int cur = 0; cur < n; cur++) {
			for (int rem = 0; rem < k; rem++) {
				for (int nxt = 0; nxt < n; nxt++) {
					if (st & (1 << nxt)) continue;
					if (rem > 0) {
						dp[st | (1 << nxt)][nxt][rem - 1] =
							min(dp[st | (1 << nxt)][nxt][rem - 1],
								dp[st][cur][rem] + dist[cur][nxt]);
					}
					dp[st | (1 << nxt)][nxt][k - 1] =
						min(dp[st | (1 << nxt)][nxt][k - 1],
							dp[st][cur][rem] + dist_org[nxt] + dist_org[cur]);
				}
			}
		}
	}
	ld ans = 9e18;
	for (int cur = 0; cur < n; cur++) {
		for (int rem = 0; rem < k; rem++) {
			ans = min(ans, dp[(1 << n) - 1][cur][rem] + dist_org[cur]);
		}
	}
	cout << setprecision(16) << fixed << ans << endl;
}