from itertools import permutations

N = int(eval(input()))

x = [0]*N

y = [0]*N

route = list(permutations(list(range(N))))



for i in range(N):

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



ans = 0

for r in route:

    for l in range(len(r)-1):

        tmp = ((x[r[l]] - x[r[l+1]])**2 + (y[r[l]] - y[r[l+1]])**2)**0.5

        ans += tmp



print((ans / len(route)))
from itertools import permutations

n = int(eval(input()))

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





pattern = list(permutations(list(range(n))))



ans = 0

for p in pattern:

    tmp = 0

    for i in range(n - 1):

        tmp += ((xy[p[i + 1]][0] - xy[p[i]][0])**2 +

                (xy[p[i + 1]][1] - xy[p[i]][1])**2)**0.5

    ans += tmp



print((ans / len(pattern)))
from itertools import permutations

N = int(eval(input()))
x = [0] * N
y = [0] * N
route = list(permutations(list(range(N))))
for i in range(N):
    x[i], y[i] = list(map(int, input().split()))
ans = 0
for r in route:
    for l in range(len(r) - 1):
        tmp = ((x[r[l]] - x[r[l + 1]]) ** 2 + (y[r[l]] - y[r[l + 1]]) ** 2) ** 0.5
        ans += tmp
print((ans / len(route)))

from itertools import permutations

n = int(eval(input()))
xy = [list(map(int, input().split())) for _ in range(n)]
pattern = list(permutations(list(range(n))))
ans = 0
for p in pattern:
    tmp = 0
    for i in range(n - 1):
        tmp += (
            (xy[p[i + 1]][0] - xy[p[i]][0]) ** 2 + (xy[p[i + 1]][1] - xy[p[i]][1]) ** 2
        ) ** 0.5
    ans += tmp
print((ans / len(pattern)))

-N = int(eval(input())) -x = [0] * N -y = [0] * N -route = list(permutations(list(range(N)))) -for i in range(N): -    x[i], y[i] = list(map(int, input().split())) +n = int(eval(input())) +xy = [list(map(int, input().split())) for _ in range(n)] +pattern = list(permutations(list(range(n)))) -for r in route: -    for l in range(len(r) - 1): -        tmp = ((x[r[l]] - x[r[l + 1]]) ** 2 + (y[r[l]] - y[r[l + 1]]) ** 2) ** 0.5 -        ans += tmp -print((ans / len(route))) +for p in pattern: +    tmp = 0 +    for i in range(n - 1): +        tmp += ( +            (xy[p[i + 1]][0] - xy[p[i]][0]) ** 2 + (xy[p[i + 1]][1] - xy[p[i]][1]) ** 2 +        ) ** 0.5 +    ans += tmp +print((ans / len(pattern)))