import sys
import math

INF = 8000000000000000.0

def main():
    input = sys.stdin.read
    data = input().split()
    
    N = int(data[0])
    K = int(data[1])
    
    x = [0] * (N + 1)
    y = [0] * (N + 1)
    
    index = 2
    for i in range(N):
        x[i] = int(data[index])
        y[i] = int(data[index + 1])
        index += 2
    
    x[N] = 0
    y[N] = 0
    
    dist = [[0] * (N + 1) for _ in range(N + 1)]
    for i in range(N + 1):
        for j in range(N + 1):
            res = (x[i] - x[j]) ** 2 + (y[i] - y[j]) ** 2
            dist[i][j] = math.sqrt(res)
    
    dp = [[[INF] * (K + 1) for _ in range(N + 1)] for _ in range(1 << N)]
    dp[0][N][K] = 0.0
    
    for bit in range(1 << N):
        for from_idx in range(N + 1):
            if from_idx < N and not (bit >> from_idx) & 1:
                continue
            for k in range(1, K + 1):
                for to in range(N):
                    if (bit >> to) & 1:
                        continue
                    dp[bit | (1 << to)][to][k - 1] = min(dp[bit | (1 << to)][to][k - 1], dp[bit][from_idx][k] + dist[from_idx][to])
            for k in range(K + 1):
                dp[bit][N][K] = min(dp[bit][N][K], dp[bit][from_idx][k] + dist[from_idx][N])
    
    print("{:.15f}".format(dp[(1 << N) - 1][N][K]))

if __name__ == "__main__":
    main()