Amr loves Geometry. One day he came up with a very interesting problem.

Amr has a circle of radius r and center in point (x, y). He wants the circle center to be in new position (x', y').

In one step Amr can put a pin to the border of the circle in a certain point, then rotate the circle around that pin by any angle and finally remove the pin.

Help Amr to achieve his goal in minimum number of steps.

Input

Input consists of 5 space-separated integers r, x, y, x' y' (1 ≤ r ≤ 105,  - 105 ≤ x, y, x', y' ≤ 105), circle radius, coordinates of original center of the circle and coordinates of destination center of the circle respectively.

Output

Output a single integer — minimum number of steps required to move the center of the circle to the destination point.

Examples

Input

2 0 0 0 4


Output

1


Input

1 1 1 4 4


Output

3


Input

4 5 6 5 6


Output

0

Note

In the first sample test the optimal way is to put a pin at point (0, 2) and rotate the circle by 180 degrees counter-clockwise (or clockwise, no matter).

<image>
 import java.util.*;
    import java.lang.Math; 
    import java.util.Arrays;
    import java.util.Scanner;
    import java.util.stream.IntStream;
    import java.io.OutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.PrintWriter;
     
    public class Problem {
       	public static void main(String[] args) {
    	   InputStream inputStream = System.in;
            OutputStream outputStream = System.out;
            Scanner in = new Scanner(inputStream);
            PrintWriter out = new PrintWriter(outputStream);
            TaskA solver = new TaskA();
            solver.solve(1, in, out);
            out.close();
    	}
    	
    	static class TaskA {
              public void solve(int testNumber, Scanner in, PrintWriter out) {
                    long r= in.nextLong();
                    long x = in.nextLong();
                    long y = in.nextLong();
                    long x1 = in.nextLong();
                    long y1 = in.nextLong();
                    
                  out.println((int)(Math.ceil(Math.sqrt((x1-x)*(x1-x)+(y1-y)*(y1-y))/(2*r))));

              }     
    	} 
    	
     
     
    	
    public int factorial(int n) {
            int fact = 1;
            int i = 1;
           while(i <= n) {
             fact *= i;
             i++;
           }
            return fact;
    }
     
    public static int BinarySearch(long temp,long[] sum,int r)
    {
    	int l=0;
    	
    	while(l<=r)
    	{
    		int mid=l+(r-l)/2;
    		if(sum[mid]==temp&&sum[mid]!=-1)
    		{
    		return mid;
    		}
    		if(sum[mid]>temp&&sum[mid]!=-1)
    			r=mid-1;
    		if(sum[mid]<temp&&sum[mid]!=-1)
    			l=mid+1;
        }
    	return -1;
    }
    public static long gcd(long x,long y)
    {
    	if(x%y==0)
    		return y;
    	else
    		return gcd(y,x%y);
    }
    public static int gcd(int x,int y)
    {
    	if(x%y==0)
    		return y;
    	else 
    		return gcd(y,x%y);
    }
    public static int abs(int a,int b)
    {
    	return (int)Math.abs(a-b);
    }
    public static long abs(long a,long b)
    {
    	return (long)Math.abs(a-b);
    }
    public static int max(int a,int b)
    {
    	if(a>b)
    		return a;
    	else
    		return b;
    }
    public static int min(int a,int b)
    {
    	if(a>b)
    		return b;
    	else 
    		return a;
    }
    public static long max(long a,long b)
    {
    	if(a>b)
    		return a;
    	else
    		return b;
    }
    public static long min(long a,long b)
    {
    	if(a>b)
    		return b;
    	else 
    		return a;
    }
     
     
    public static long pow(long n,long p,long m)
    {
    	 long  result = 1;
    	  if(p==0)
    	    return 1;
    	if (p==1)
    	    return n;
    	while(p!=0)
    	{
    	    if(p%2==1)
    	        result *= n;
    	    if(result>=m)
    	    result%=m;
    	    p >>=1;
    	    n*=n;
    	    if(n>=m)
    	    n%=m;
    	}
    	return result;
    }
    public static long pow(long n,long p)
    {
    	long  result = 1;
    	  if(p==0)
    	    return 1;
    	if (p==1)
    	    return n;
    	while(p!=0)
    	{
    	    if(p%2==1)
    	        result *= n;	    
    	    p >>=1;
    	    n*=n;	    
    	}
    	return result;
     
    }
     
    static long sort(int a[]){  
         int n=a.length;
    	int b[]=new int[n];	
    	return mergeSort(a,b,0,n-1);
         
    }
     
    static long mergeSort(int a[],int b[],long left,long right){
         long c=0;
         if(left<right){   
          long mid=left+(right-left)/2;
    	 c= mergeSort(a,b,left,mid);
    	 c+=mergeSort(a,b,mid+1,right);
    	 c+=merge(a,b,left,mid+1,right); 
         }	
    	return c;	 
    }
    static long merge(int a[],int  b[],long left,long mid,long right){
         long c=0;int i=(int)left;int j=(int)mid; int k=(int)left;
         while(i<=(int)mid-1&&j<=(int)right){ 
              if(a[i]<=a[j]){
                   b[k++]=a[i++]; 
              }
              else{ 
                   b[k++]=a[j++];c+=mid-i;
              }
         }
         
         while (i <= (int)mid - 1)   
                 b[k++] = a[i++]; 
         while (j <= (int)right)
                 b[k++] = a[j++];
         for (i=(int)left; i <= (int)right; i++) 
    	        a[i] = b[i];
    	        return c; 
         }
     
    }