from itertools import permutations



N = int(eval(input()))

x = [0] * N

y = [0] * N

for i in range(N):

    x[i], y[i] = [int(x) for x in input().split()]



listP = list(permutations(list(range(N)), N))

sum_d = 0

for p in listP:

    for i in range(1, N):

        sum_d += ((x[p[i]] - x[p[i - 1]]) ** 2 + (y[p[i]] - y[p[i - 1]]) ** 2) ** 0.5



print((sum_d / len(listP)))
N = int(eval(input()))

x = [0] * N

y = [0] * N

for i in range(N):

    x[i], y[i] = [int(x) for x in input().split()]



sum_d = 0

for i in range(N):

    for j in range(i + 1, N):

        sum_d += ((x[j] - x[i]) ** 2 + (y[j] - y[i]) ** 2) ** 0.5



# (sum_d / NC2) * (N - 1)

print((2 * sum_d / N))
from itertools import permutations

N = int(eval(input()))
x = [0] * N
y = [0] * N
for i in range(N):
    x[i], y[i] = [int(x) for x in input().split()]
listP = list(permutations(list(range(N)), N))
sum_d = 0
for p in listP:
    for i in range(1, N):
        sum_d += ((x[p[i]] - x[p[i - 1]]) ** 2 + (y[p[i]] - y[p[i - 1]]) ** 2) ** 0.5
print((sum_d / len(listP)))

N = int(eval(input()))
x = [0] * N
y = [0] * N
for i in range(N):
    x[i], y[i] = [int(x) for x in input().split()]
sum_d = 0
for i in range(N):
    for j in range(i + 1, N):
        sum_d += ((x[j] - x[i]) ** 2 + (y[j] - y[i]) ** 2) ** 0.5
# (sum_d / NC2) * (N - 1)
print((2 * sum_d / N))

-from itertools import permutations - -listP = list(permutations(list(range(N)), N)) -for p in listP: -    for i in range(1, N): -        sum_d += ((x[p[i]] - x[p[i - 1]]) ** 2 + (y[p[i]] - y[p[i - 1]]) ** 2) ** 0.5 -print((sum_d / len(listP))) +for i in range(N): +    for j in range(i + 1, N): +        sum_d += ((x[j] - x[i]) ** 2 + (y[j] - y[i]) ** 2) ** 0.5 +# (sum_d / NC2) * (N - 1) +print((2 * sum_d / N))