import java.util.*;

public class Main {
  static int[] par;
  static int[] rank;
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    par = new int[n];
    rank = new int[n];
    long[] x = new long[n];
    long[] y = new long[n];
    init(n);
    for(int i = 0; i < n; i++) {
      x[i] = sc.nextLong();
      y[i] = sc.nextLong();
    }
    for(int i = 0; i < n - 1; i++) {
      for(int j = i + 1; j < n; j++) {
        if(((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j])) <= 100) unite(i, j);
      }
    }
    double ans = 0;
    for(int i = 0; i < n - 1; i++) {
      for(int j = i + 1; j < n; j++) {
        if(same(i, j)) ans = Math.max(ans, Math.sqrt(((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j])))); 
      }
    }
    ans += 2;
    if(n == 0) ans = 1;
    System.out.println(ans);
  }
  static void init(int m) {
      for(int i = 0; i < m; i++) {
        par[i] = i;
        rank[i] = 0;
      }
    }
  static int find(int x) {
      if(par[x] == x) {
        return x;
      } else {
        return par[x] = find(par[x]);
      }
    }
  static void unite(int x, int y) {
      x = find(x);
      y = find(y);
      if(x != y) {
        if(rank[x] < rank[y]) {
          par[x] = y;
        } else {
          par[y] = x;
          if(rank[x] == rank[y]) {
            rank[x]++;
          }
        }
      }
    }
  static boolean same(int x, int y) {
      return find(x) == find(y);
    }
}