#include <iostream>
#include <algorithm>
using namespace std;

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n):i({0}),n({n}){}range(int i,int n):i({i}),n({n}){}I& begin(){return i;}I& end(){return n;}};

class Point {
public:
  int x, y;
  Point(void) {}
  Point(int _x, int _y) { x = _x; y = _y; }
  bool operator==(const Point& other) const { return x == other.x && y == other.y; }
  int distdist(const Point& other) const { return (x - other.x) * (x - other.x) + (y - other.y) * (y - other.y); }
};

const int inf = 987654321;

int main(void) {
  int n; scanf("%d", &n);
  vector<Point> v(n);
  for(int i : range(n)) {
    int x, y; scanf("%d%d", &x, &y);
    v[i] = Point(x, y);
  }
  vector<vector<int>> cost(n, vector<int>(n, 0)),
                      route(n, vector<int>(n, inf));
  for(int i : range(n)) {
    route[i][i] = 0;
  }
  for(int i : range(n-1)) {
    for(int j : range(i+1, n)) {
      int dd = v[i].distdist(v[j]);
      cost[i][j] = dd;
      cost[j][i] = dd;
      if(dd > 10 * 10) { continue; }
      route[i][j] = 1;
      route[j][i] = 1;
    }
  }
  for(int k : range(n)) {
    for(int i : range(n)) {
      for(int j : range(n)) {
        route[i][j] = min(route[i][j], route[i][k] + route[k][j]);
      }
    }
  }
  int res = 0;
  for(int i : range(n)) {
    for(int j : range(n)) {
      if(route[i][j] >= inf) { continue; }
      res = max(res, cost[i][j]);
    }
  }
  printf("%lf\n",  sqrt(res) + 1 + (n>0));
  return 0;
}