import std.algorithm, std.array, std.container, std.range, std.bitmanip;
import std.numeric, std.math, std.bigint, std.random, core.bitop;
import std.string, std.conv, std.stdio, std.typecons;

struct point {
  int x, y;

  point opBinary(string op)(point rhs) {
    static if (op == "+") return point(x + rhs.x, y + rhs.y);
    else static if (op == "-") return point(x - rhs.x, y - rhs.y);
  }

  int abs2() { return x ^^ 2 + y ^^ 2; }
}

class UnionFind {
  int[] par;

  this(int n) {
    par = new int[](n);
    par[] = -1;
  }

  int find(int i) {
    if (par[i] < 0) {
      return i;
    } else {
      par[i] = find(par[i]);
      return par[i];
    }
  }

  void unite(int i, int j) {
    auto pi = find(i), pj = find(j);
    if (pi != pj) par[j] = pi;
  }
}

void main()
{
  auto n = readln.chomp.to!int;
  auto pi = iota(n)
    .map!(_ => readln.split.map!(to!int))
    .map!(rd => point(rd[0], rd[1])).array;

  auto uf = new UnionFind(n);
  foreach (i; 0..n - 1)
    foreach (j; i..n)
      if ((pi[i] - pi[j]).abs2 <= 100)
        uf.unite(i, j);

  int[][int] h;
  foreach (i; 0..n)
    h[uf.find(i)] ~= i;

  auto maxDist = 0;
  foreach (qi; h.byValue)
    foreach (i; 0..qi.length - 1)
      foreach (j; i + 1..qi.length)
        maxDist = max(maxDist, (pi[qi[i]] - pi[qi[j]]).abs2);

  writefln("%f", n == 0 ? 1 : maxDist.to!real.sqrt + 2);
}