import itertools



n=int(eval(input()))

ab = []

for _ in range(n):

    a, b = (int(x) for x in input().split())

    ab.append([a, b])



narabi = [0+i for i in range(n)]



ans = 0

count = 0

for v in itertools.permutations(narabi, n):

    count += 1

    tmp_len = 0

    for i in range(1,n):

        x, y = abs(ab[v[i-1]][0]-ab[v[i]][0])**2, abs(ab[v[i-1]][1]-ab[v[i]][1])**2

        tmp_len += (x + y)**0.5

    ans += tmp_len



print((ans/count))
import itertools



n=int(eval(input()))

ab = []

for _ in range(n):

    a, b = (int(x) for x in input().split())

    ab.append([a, b])



memo = []

for i in range(n):

    memo.append(i)



ans = 0

count = 0

for v in itertools.permutations(memo, n):

    count += 1

    tmp_root = 0

    for i in range(1, n):

        tmp_root += ((ab[v[i-1]][0]-ab[v[i]][0])**2+(ab[v[i-1]][1]-ab[v[i]][1])**2)**0.5

    ans += tmp_root



print((ans/count))
import itertools

n = int(eval(input()))
ab = []
for _ in range(n):
    a, b = (int(x) for x in input().split())
    ab.append([a, b])
narabi = [0 + i for i in range(n)]
ans = 0
count = 0
for v in itertools.permutations(narabi, n):
    count += 1
    tmp_len = 0
    for i in range(1, n):
        x, y = (
            abs(ab[v[i - 1]][0] - ab[v[i]][0]) ** 2,
            abs(ab[v[i - 1]][1] - ab[v[i]][1]) ** 2,
        )
        tmp_len += (x + y) ** 0.5
    ans += tmp_len
print((ans / count))

import itertools

n = int(eval(input()))
ab = []
for _ in range(n):
    a, b = (int(x) for x in input().split())
    ab.append([a, b])
memo = []
for i in range(n):
    memo.append(i)
ans = 0
count = 0
for v in itertools.permutations(memo, n):
    count += 1
    tmp_root = 0
    for i in range(1, n):
        tmp_root += (
            (ab[v[i - 1]][0] - ab[v[i]][0]) ** 2 + (ab[v[i - 1]][1] - ab[v[i]][1]) ** 2
        ) ** 0.5
    ans += tmp_root
print((ans / count))

-narabi = [0 + i for i in range(n)] +memo = [] +for i in range(n): +    memo.append(i) -for v in itertools.permutations(narabi, n): +for v in itertools.permutations(memo, n): -    tmp_len = 0 +    tmp_root = 0 -        x, y = ( -            abs(ab[v[i - 1]][0] - ab[v[i]][0]) ** 2, -            abs(ab[v[i - 1]][1] - ab[v[i]][1]) ** 2, -        ) -        tmp_len += (x + y) ** 0.5 -    ans += tmp_len +        tmp_root += ( +            (ab[v[i - 1]][0] - ab[v[i]][0]) ** 2 + (ab[v[i - 1]][1] - ab[v[i]][1]) ** 2 +        ) ** 0.5 +    ans += tmp_root