import itertools



n = int(eval(input()))



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



dist_list = list()

dist_way = list(itertools.permutations(list(range(n))))



for dist_i in dist_way:

  dist = 0

  for i in range(len(dist_i)-1):

    dist += ((city_pos[dist_i[i]][0] - city_pos[dist_i[i+1]][0])**2 + (city_pos[dist_i[i]][1] - city_pos[dist_i[i+1]][1])**2)**(0.5)

  

  dist_list.append(dist)

  

print((sum(dist_list)/len(dist_list)))
import itertools



n = int(eval(input()))

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



cand = list(itertools.permutations(list(range(n)), n))



ans = 0

for cand_i in cand:

  for i in range(n-1):

    ans += ((XY[cand_i[i]][0]-XY[cand_i[i+1]][0])**2+(XY[cand_i[i]][1]-XY[cand_i[i+1]][1])**2)**(1/2)



print((ans/len(cand)))
import itertools

n = int(eval(input()))
city_pos = [list(map(int, input().split())) for _ in range(n)]
dist_list = list()
dist_way = list(itertools.permutations(list(range(n))))
for dist_i in dist_way:
    dist = 0
    for i in range(len(dist_i) - 1):
        dist += (
            (city_pos[dist_i[i]][0] - city_pos[dist_i[i + 1]][0]) ** 2
            + (city_pos[dist_i[i]][1] - city_pos[dist_i[i + 1]][1]) ** 2
        ) ** (0.5)
    dist_list.append(dist)
print((sum(dist_list) / len(dist_list)))

import itertools

n = int(eval(input()))
XY = [list(map(int, input().split())) for _ in range(n)]
cand = list(itertools.permutations(list(range(n)), n))
ans = 0
for cand_i in cand:
    for i in range(n - 1):
        ans += (
            (XY[cand_i[i]][0] - XY[cand_i[i + 1]][0]) ** 2
            + (XY[cand_i[i]][1] - XY[cand_i[i + 1]][1]) ** 2
        ) ** (1 / 2)
print((ans / len(cand)))

-city_pos = [list(map(int, input().split())) for _ in range(n)] -dist_list = list() -dist_way = list(itertools.permutations(list(range(n)))) -for dist_i in dist_way: -    dist = 0 -    for i in range(len(dist_i) - 1): -        dist += ( -            (city_pos[dist_i[i]][0] - city_pos[dist_i[i + 1]][0]) ** 2 -            + (city_pos[dist_i[i]][1] - city_pos[dist_i[i + 1]][1]) ** 2 -        ) ** (0.5) -    dist_list.append(dist) -print((sum(dist_list) / len(dist_list))) +XY = [list(map(int, input().split())) for _ in range(n)] +cand = list(itertools.permutations(list(range(n)), n)) +ans = 0 +for cand_i in cand: +    for i in range(n - 1): +        ans += ( +            (XY[cand_i[i]][0] - XY[cand_i[i + 1]][0]) ** 2 +            + (XY[cand_i[i]][1] - XY[cand_i[i + 1]][1]) ** 2 +        ) ** (1 / 2) +print((ans / len(cand)))