N, K = map(int, input().split())
place = [list(map(int, input().split())) for _ in range(N)]

def distance(x1, y1, x2, y2):
    return ((x2-x1)**2 + (y2-y1)**2) ** 0.5

dist = [[0]*N for _ in range(N)]
for i in range(N):
    x1, y1 = place[i]
    for j in range(N):
        x2, y2 = place[j]
        dist[i][j] = distance(x1, y1, x2, y2)
dist2 = [[0]*N for _ in range(N)]
for i in range(N):
    x1, y1 = place[i]
    for j in range(N):
        x2, y2 = place[j]
        dist2[i][j] = distance(x1, y1, 0, 0)+distance(0, 0, x2, y2)

# dp[i][j][k] i:現在地 j:持っているプレゼントの数 k:既に届けた場所の集合
INF = 10**18
dp = [[[INF]*(1<<N) for _ in range(K)] for _ in range(N)]
for i in range(N):
    x, y = place[i]
    dp[i][K-1][1<<i] = distance(0, 0, x, y)
for bit in range(1<<N):
    for i in range(N):
        for j in range(K):
            if dp[i][j][bit] == INF:
                continue
            for k in range(N):
                if not 1<<k & bit:
                    if 1 <= j:
                        dp[k][j-1][bit|1<<k] = min(dp[k][j-1][bit|1<<k], dp[i][j][bit]+dist[i][k])
                    dp[k][K-1][bit|1<<k] = min(dp[k][K-1][bit|1<<k], dp[i][j][bit]+dist2[i][k])

ans = 10**18
for i in range(N):
    x, y = place[i]
    for j in range(K):
        ans = min(ans, dp[i][j][(1<<N)-1]+distance(x, y, 0, 0))

print(ans)