#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import itertools

# %%
N = int(readline())
m = map(float, read().split())
XYZ = zip(m, m, m)
P = next(XYZ)
XYZ = [(x - P[0], y - P[1], z - P[2]) for x, y, z in XYZ]


# %%
def dist(i, j, k):
    v1 = [XYZ[i][n] - XYZ[j][n] for n in range(3)]
    v2 = [XYZ[i][n] - XYZ[k][n] for n in range(3)]
    v = [v1[1] * v2[2] - v1[2] * v2[1],
         v1[2] * v2[0] - v1[0] * v2[2],
         v1[0] * v2[1] - v1[1] * v2[0]]
    x, y, z = XYZ[i]
    c = v[0] * x + v[1] * y + v[2] * z
    return abs(c) / (v[0]**2 + v[1]**2 + v[2] ** 2) ** .5


# %%
nums = (dist(i, j, k) for i, j, k in itertools.combinations(range(N), 3))
print(sum(nums))