import java.io.PipedInputStream;
import java.util.*;

class pair implements Comparable{
	int num;
	double kyori;
	pair(int num,double kyori){
		this.num=num;
		this.kyori=kyori;
	}
	@Override
	public int compareTo(Object o) {
		// TODO Auto-generated method stub
		return (int)(this.kyori-((pair)o).kyori);
	}
	
}
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long ans=0;
		int n = sc.nextInt();
		boolean[] used = new boolean[n];
		int[] x = new int[n];
		int[] y = new int[n];
		for(int i=0;i<n;i++){
			x[i]=sc.nextInt();
			y[i]=sc.nextInt();
		}
		PriorityQueue<pair> queue = new PriorityQueue<>();
		queue.add(new pair(0, 0));
		while(true){
			pair now = queue.poll();
			if(used[now.num]) continue;
			ans=Math.max(ans,(long)Math.ceil(now.kyori/10)*10);
			used[now.num]=true;
			if(now.num==n-1) break;
			for(int i=0;i<n;i++){
				if(used[i])continue;
				double aaa = Math.sqrt(Math.pow(x[now.num]-x[i],2)+Math.pow(y[now.num]-y[i],2));
				queue.add(new pair(i, aaa));
			}
		}
		System.out.println(ans);
	}
}