n=int(eval(input()))

s=0

xy=[tuple(map(int,input().split())) for _ in range(n)]

import itertools

l=[i for i in range(1,n+1)]

for y in itertools.permutations(l):

    for i in range(n-1):

        s+=((xy[y[i]-1][0]-xy[y[i+1]-1][0])**2+(xy[y[i]-1][1]-xy[y[i+1]-1][1])**2)**0.5

e=1

for i in range(1,n+1):

    e*=i

print((s/e))

n=int(eval(input()))

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

import itertools as it

ans=0

for i in it.permutations(list(range(n)),n):

    x=xy[i[0]][0]

    y=xy[i[0]][1]

    for k in range(1,n):

        j=i[k]

        ans+=((x-xy[j][0])**2+(y-xy[j][1])**2)**0.5

        x=xy[j][0]

        y=xy[j][1]

N=1

for i in range(1,n+1):

    N*=i

print((ans/N))

n = int(eval(input()))
s = 0
xy = [tuple(map(int, input().split())) for _ in range(n)]
import itertools

l = [i for i in range(1, n + 1)]
for y in itertools.permutations(l):
    for i in range(n - 1):
        s += (
            (xy[y[i] - 1][0] - xy[y[i + 1] - 1][0]) ** 2
            + (xy[y[i] - 1][1] - xy[y[i + 1] - 1][1]) ** 2
        ) ** 0.5
e = 1
for i in range(1, n + 1):
    e *= i
print((s / e))

n = int(eval(input()))
xy = [list(map(int, input().split())) for _ in range(n)]
import itertools as it

ans = 0
for i in it.permutations(list(range(n)), n):
    x = xy[i[0]][0]
    y = xy[i[0]][1]
    for k in range(1, n):
        j = i[k]
        ans += ((x - xy[j][0]) ** 2 + (y - xy[j][1]) ** 2) ** 0.5
        x = xy[j][0]
        y = xy[j][1]
N = 1
for i in range(1, n + 1):
    N *= i
print((ans / N))

-s = 0 -xy = [tuple(map(int, input().split())) for _ in range(n)] -import itertools +xy = [list(map(int, input().split())) for _ in range(n)] +import itertools as it -l = [i for i in range(1, n + 1)] -for y in itertools.permutations(l): -    for i in range(n - 1): -        s += ( -            (xy[y[i] - 1][0] - xy[y[i + 1] - 1][0]) ** 2 -            + (xy[y[i] - 1][1] - xy[y[i + 1] - 1][1]) ** 2 -        ) ** 0.5 -e = 1 +ans = 0 +for i in it.permutations(list(range(n)), n): +    x = xy[i[0]][0] +    y = xy[i[0]][1] +    for k in range(1, n): +        j = i[k] +        ans += ((x - xy[j][0]) ** 2 + (y - xy[j][1]) ** 2) ** 0.5 +        x = xy[j][0] +        y = xy[j][1] +N = 1 -    e *= i -print((s / e)) +    N *= i +print((ans / N))