/**
 * I think this is the easiest problem. Straight forward O(n^2) problem.
 */

import kotlin.math.pow
import kotlin.math.sqrt

fun main() {
  val reader = System.`in`.bufferedReader()
  val n = reader.readLine().toInt()
  val input = reader.lineSequence().take(n).map { string ->
    string.split(" ", limit = 3)
      .map { it.toDouble() }
      .let { (x, y, z) -> Coordinate(x, y, z) }
  }.toList()
  println((0 until input.size - 2).minOf { index ->
    input[index].let { current ->
      input.drop(index + 1).minOf { current.distance(it) }
    }
  })
}

typealias Coordinate = Triple<Double, Double, Double>

inline fun Coordinate.distance(other: Coordinate) =
  sqrt((first - other.first).pow(2) + (second - other.second).pow(2) + (third - other.third).pow(2))