from itertools import permutations

from math import hypot



n = int(eval(input()))

cnt = 0

dis = 0



li = []

for i in range(n):

    x,y = list(map(int,input().split()))

    li.append([x, y])



ptn = list(range(n))



for a in permutations(ptn):

    cnt += 1

    for i, j in zip(a,a[1:]):

        x1, y1 = li[i]

        x2, y2 = li[j]

        dis += hypot(x1-x2, y1-y2)



print((dis/cnt))
from itertools import permutations

from math import hypot



n = int(eval(input()))

cnt = 0

dis = 0



li = []

for i in range(n):

    x,y = list(map(int,input().split()))

    li.append([x, y])



for a in permutations(li):

    cnt += 1

    for (x1,y1),(x2,y2) in zip(a,a[1:]):

        dis += hypot(x1-x2, y1-y2)



print((dis/cnt))
from itertools import permutations
from math import hypot

n = int(eval(input()))
cnt = 0
dis = 0
li = []
for i in range(n):
    x, y = list(map(int, input().split()))
    li.append([x, y])
ptn = list(range(n))
for a in permutations(ptn):
    cnt += 1
    for i, j in zip(a, a[1:]):
        x1, y1 = li[i]
        x2, y2 = li[j]
        dis += hypot(x1 - x2, y1 - y2)
print((dis / cnt))

from itertools import permutations
from math import hypot

n = int(eval(input()))
cnt = 0
dis = 0
li = []
for i in range(n):
    x, y = list(map(int, input().split()))
    li.append([x, y])
for a in permutations(li):
    cnt += 1
    for (x1, y1), (x2, y2) in zip(a, a[1:]):
        dis += hypot(x1 - x2, y1 - y2)
print((dis / cnt))

-ptn = list(range(n)) -for a in permutations(ptn): +for a in permutations(li): -    for i, j in zip(a, a[1:]): -        x1, y1 = li[i] -        x2, y2 = li[j] +    for (x1, y1), (x2, y2) in zip(a, a[1:]):