#include<stdio.h>
#include<math.h>
double x[16], y[16];
double dist(long long int i, long long int j)
{
	return sqrt((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]));
}
double dp[20004][16][16];
int main()
{
	long long int n, k;
	scanf("%lld %lld", &n, &k);
	long long int i, j, l, c;
	for (i = 0; i < n; i++)
		scanf("%lf%lf", &x[i + 1], &y[i + 1]);
	x[0] = y[0] = 0;
	for (i = 0; i < (1 << (n + 1)); i++)
		for (j = 0; j <= n; j++)
			for (l = 0; l <= k; l++)
				dp[i][j][l] = 1e18;
	dp[1][0][k] = 0;
	for (l = 0; l < (1 << (n + 1)); l++)
	{
		for (i = n; i >= 0; i--)
		{
			for (c = 0; c <= k; c++)
			{
				dp[l | 1][0][k] = fmin(dp[l | 1][0][k], dp[l][i][c] + dist(0, i));
				if (c == 0)
					continue;
				for (j = 1; j <= n; j++)
				{
					if (((l >> j) & 1) > 0)
						continue;
					dp[l | (1 << j)][j][c - 1] = fmin(dp[l | (1 << j)][j][c - 1], dp[l][i][c] + dist(i, j));
				}
			}
		}
	}
	printf("%.20lf\n", dp[(1 << (n + 1)) - 1][0][k]);
	return 0;
}