#!/usr/bin/env python3
# @EXPECTED_RESULTS@: ACCEPTED,WRONG_ANSWER
from math import sqrt
import sys

# n = int(input())
ps = []
for line in sys.stdin.readlines()[1:]:
    ps.append(list(map(int, line.split())))
B = 10
L = (10**9 + B - 1) // B
boxes = [[[[] for _ in range(B)] for _ in range(B)] for _ in range(B)]
for [x, y, z] in ps:
    boxes[x // L][y // L][z // L].append((x, y, z))

ans = 3 * 10**9
for b1 in boxes:
    for b2 in b1:
        for b3 in b2:
            for (x1, y1, z1) in b3:
                for (x2, y2, z2) in b3:
                    d = sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2 + (z1 - z2) ** 2)
                    # By probability, d=0 won't happen in the input
                    if d > 0:
                        ans = min(ans, d)
print(ans)