import numpy as np

N = int(eval(input()))

R = np.array([list(map(int,input().split())) for i in range(N)])

print((sum(np.linalg.norm(i-j) for i in R for j in R)/N))
import numpy as np

N = int(eval(input()))

R = np.array([list(map(int,input().split())) for n in range(N)])

print((sum(np.linalg.norm(i-j) for i in R for j in R)/N))
import numpy as np

N = int(eval(input()))
R = np.array([list(map(int, input().split())) for i in range(N)])
print((sum(np.linalg.norm(i - j) for i in R for j in R) / N))

import numpy as np

N = int(eval(input()))
R = np.array([list(map(int, input().split())) for n in range(N)])
print((sum(np.linalg.norm(i - j) for i in R for j in R) / N))

-R = np.array([list(map(int, input().split())) for i in range(N)]) +R = np.array([list(map(int, input().split())) for n in range(N)])