import std.algorithm, std.conv, std.range, std.stdio, std.string;
import std.math;      // math functions

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

  auto dij = new int[][](n, n);
  foreach (i; 0..n)
    foreach (j; i+1..n)
      dij[i][j] = dij[j][i] = (pi[i] - pi[j]).hypot2;

  auto uf = new unionFind(n);
  foreach (i; 0..n)
    foreach (j; i+1..n)
      if (i != j && dij[i][j] <= 100)
        uf.unite(i, j);

  auto gi = new size_t[][](n);
  foreach (i; 0..n) gi[uf.find(i)] ~= i;

  if (n == 0) {
    writeln(1);
  } else {
    auto maxD = gi.filter!"!a.empty".map!(g => dij.indexed(g).map!(di => di.indexed(g)).joiner.fold!max).fold!max;
    writefln("%.7f", maxD.to!real.sqrt + 2);
  }
}

alias UnionFind!size_t unionFind;
alias Point!int point;

class UnionFind(T) {
  T[] p; // parent
  T s; // sentinel

  this(T n) {
    p = new T[](n);
    s = n + 1;
    p[] = s;
  }

  T find(T i) {
    if (p[i] == s) {
      return i;
    } else {
      p[i] = find(p[i]);
      return p[i];
    }
  }

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

struct Point(T) {
  T x, y;

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

  T hypot2() { return x ^^ 2 + y ^^ 2; }
}