def d(x,y):

    return ((x[0]-y[0])**2+(x[1]-y[1])**2)**(1/2)



import itertools

ans=0

k=1

n= int(eval(input()))

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

l=[i for i in range(n)]

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

    for i in range(n-1):

        ans+=d(xy[v[i]],xy[v[i+1]])

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

    k*=i

print((ans/k))
def d(x,y):

    return ((x[0]-y[0])**2+(x[1]-y[1])**2)**(1/2)

n= int(eval(input()))

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

ans=0

for i in range(n):

    for j in range(n):

        ans+=d(x[i],x[j])

print((ans/n))
def d(x, y):
    return ((x[0] - y[0]) ** 2 + (x[1] - y[1]) ** 2) ** (1 / 2)


import itertools

ans = 0
k = 1
n = int(eval(input()))
xy = [list(map(int, input().split())) for i in range(n)]
l = [i for i in range(n)]
for v in itertools.permutations(l, n):
    for i in range(n - 1):
        ans += d(xy[v[i]], xy[v[i + 1]])
for i in range(1, n + 1):
    k *= i
print((ans / k))

def d(x, y):
    return ((x[0] - y[0]) ** 2 + (x[1] - y[1]) ** 2) ** (1 / 2)


n = int(eval(input()))
x = [list(map(int, input().split())) for i in range(n)]
ans = 0
for i in range(n):
    for j in range(n):
        ans += d(x[i], x[j])
print((ans / n))

-import itertools - +n = int(eval(input())) +x = [list(map(int, input().split())) for i in range(n)] -k = 1 -n = int(eval(input())) -xy = [list(map(int, input().split())) for i in range(n)] -l = [i for i in range(n)] -for v in itertools.permutations(l, n): -    for i in range(n - 1): -        ans += d(xy[v[i]], xy[v[i + 1]]) -for i in range(1, n + 1): -    k *= i -print((ans / k)) +for i in range(n): +    for j in range(n): +        ans += d(x[i], x[j]) +print((ans / n))