import java.util.ArrayList;
import java.util.Scanner;

public class Main94 {
	public static void main(String[] args) {
		Main94 p = new Main94();
	}

	public Main94() {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] x = new int[n];
		int[] y = new int[n];
		for (int i = 0; i < x.length; i++) {
			x[i] = sc.nextInt();
			y[i] = sc.nextInt();
		}
		solve(x, y);
	}

	
	public void solve(int[] x, int[] y) {
		if(x.length==0){
			System.out.println(1);
			return;
		}
			
		uf(x.length);
		for(int i=0;i<x.length;i++){
			for(int j=i+1;j<x.length;j++){
				boolean isCross = isCrossCircle(x[i], y[i], 5, x[j], y[j], 5);
				if(isCross)
					unite(i, j);
			}
		}
		
		long dist = 0;
		for(int i=0;i<x.length;i++){
			for(int j=i+1;j<x.length;j++){
				if(same(i,j))
					dist =Math.max(dist, (x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]));
			}
		}
		
		if(dist == 0)
			System.out.println(2);
		else
			System.out.println(Math.sqrt(dist)+2);
		
	}
	
	int[] par;
	int[] rank;
	private void uf(int n){
		par = new int[n];
		rank = new int[n];
		for(int i=0;i<n;i++){
			par[i] = i;
			rank[i] = 0;
		}
	}
	
	// 木の根を返す
	private int find(int x){
		if(par[x] == x)
			return x;
		else
			return par[x] =find(par[x]);
	}
	
	// 併合
	private void unite(int x, int y){
		x = find(x);
		y = find(y);
		
		// すでに同じグループ
		if(x==y)
			return;
		
		if(rank[x]<rank[y]){
			par[x] = y;
		}else{
			par[y] = x;
			if(rank[x]==rank[y])
				rank[x]++;
		}
	}
	
	// 同じグループなら真
	private boolean same(int x, int y){
		return find(x) == find(y);
	}

	// 円が交差しているなら真
	private boolean isCrossCircle(long x1, long y1, long r1, long x2, long y2, long r2){
		// 三平方の定理から求める
		long a = (x1-x2)*(x1-x2);
		long b = (y1-y2)*(y1-y2);
		long c = (r1+r2)*(r1+r2);
		return a+b <= c;
	}
}