N = int(eval(input()))

L=[[int(j) for j in input().split()] for i in range(N)]

from math import factorial, sqrt

S = 0



def solve(L, r):

    global S

    if len(L) == 0:

        for i in range(N-1):

            x, y = r[i]

            x2, y2 = r[i+1]

            S += sqrt((x - x2)**2 + (y - y2)**2)

    for i, v in enumerate(L):

        if len(L) == N:

            solve(L[:i] + L[i+1:], [v])

        else:

            solve(L[:i] + L[i+1:], r + [v])



solve(L, [])

print((S/factorial(N)))
N = int(eval(input()))

L=[[int(j) for j in input().split()] for i in range(N)]

from math import factorial, sqrt

from itertools import permutations

S = 0

def k(a, b):

    return sqrt((a[0] - b[0])**2 + (a[1] - b[1])**2)

for l in permutations(L):

    S += sum([k(l[i], l[i+1]) for i in range(N-1)])



print((S/factorial(N)))
N = int(eval(input()))
L = [[int(j) for j in input().split()] for i in range(N)]
from math import factorial, sqrt

S = 0


def solve(L, r):
    global S
    if len(L) == 0:
        for i in range(N - 1):
            x, y = r[i]
            x2, y2 = r[i + 1]
            S += sqrt((x - x2) ** 2 + (y - y2) ** 2)
    for i, v in enumerate(L):
        if len(L) == N:
            solve(L[:i] + L[i + 1 :], [v])
        else:
            solve(L[:i] + L[i + 1 :], r + [v])


solve(L, [])
print((S / factorial(N)))

N = int(eval(input()))
L = [[int(j) for j in input().split()] for i in range(N)]
from math import factorial, sqrt
from itertools import permutations

S = 0


def k(a, b):
    return sqrt((a[0] - b[0]) ** 2 + (a[1] - b[1]) ** 2)


for l in permutations(L):
    S += sum([k(l[i], l[i + 1]) for i in range(N - 1)])
print((S / factorial(N)))

+from itertools import permutations -def solve(L, r): -    global S -    if len(L) == 0: -        for i in range(N - 1): -            x, y = r[i] -            x2, y2 = r[i + 1] -            S += sqrt((x - x2) ** 2 + (y - y2) ** 2) -    for i, v in enumerate(L): -        if len(L) == N: -            solve(L[:i] + L[i + 1 :], [v]) -        else: -            solve(L[:i] + L[i + 1 :], r + [v]) +def k(a, b): +    return sqrt((a[0] - b[0]) ** 2 + (a[1] - b[1]) ** 2) -solve(L, []) +for l in permutations(L): +    S += sum([k(l[i], l[i + 1]) for i in range(N - 1)])