def popcount32(x):
    x = x - ((x >> 1) & 0x55555555)
    x = (x & 0x33333333) + ((x >> 2) & 0x33333333)
    x = (x + (x >> 4)) & 0x0F0F0F0F
    x += x >> 8
    x += x >> 16
    return x & 0x0000003F


n, k = map(int, input().split())
XY = [list(map(int, input().split())) for _ in range(n)]

dist = [[1 << 60] * n for _ in range(1 << n)]
for i in range(n):
    x, y = XY[i]
    d = (x**2 + y**2) ** 0.5
    dist[1 << i][i] = d

for bit in range(1, 1 << n):
    for i in range(n):
        if not (bit >> i & 1):
            continue
        for j in range(n):
            if bit >> j & 1:
                continue
            d = ((XY[i][0] - XY[j][0]) ** 2 + (XY[i][1] - XY[j][1]) ** 2) ** 0.5
            dist[bit | 1 << j][j] = min(dist[bit | 1 << j][j], dist[bit][i] + d)

D = [0] * (1 << n)
for bit in range(1, 1 << n):
    mi = 1 << 60
    if popcount32(bit) > k:
        D[bit] = mi
        continue
    for i in range(n):
        if bit >> i & 1:
            d = dist[bit][i] + (XY[i][0] ** 2 + XY[i][1] ** 2) ** 0.5
            mi = min(mi, d)
    D[bit] = mi

dp = [1 << 60] * (1 << n)
dp[0] = 0

for bit in range(1, 1 << n):
    sub = bit
    while sub:
        dp[bit] = min(dp[bit], dp[bit ^ sub] + D[sub])
        sub = (sub - 1) & bit

print(dp[-1])