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).

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import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import java.lang.*;
import java.util.ArrayList;
import java.math.BigInteger;
public class me {

public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner br = new Scanner(System.in);
       double n=br.nextDouble();
       double x1=br.nextDouble();
       double y1=br.nextDouble();
       double x2=br.nextDouble();
       double y2=br.nextDouble();
       System.out.print((int)Math.ceil((Math.sqrt(Math.pow(Math.abs(x1-x2),2)+Math.pow(Math.abs(y2-y1),2)))/(2*n)));
}
     
     

    public static long  ways(int n, int r, long MOD)
    {
      //  vector<long long> f(n + 1,1);
        long f[]=new long[n+1];
        Arrays.fill(f,1);
        for (int i=2; i<=n;i++)
            f[i]= (f[i-1]*i) % MOD;
        return (f[n]*((InverseEuler(f[r], MOD) * InverseEuler(f[n-r], MOD)) % MOD)) % MOD;
    }  
    
                  
                  
                  
                   /*THIS IS FOR THE INVERSE EULER*/
    public static long  InverseEuler(long n, long MOD)
    {
        return pow(n,MOD-2,MOD);
    }
    
    
    
                   
                   /*THIS ID THE CHECK FOR THE PRIME*/
    static int isPrime(int n) {
    for(int i=2;i<n;i++) {
        if(n%i==0)
            return 0;
    }
    return 1;
}
    
    
    
                          /*TO CHECK FOR THE GCD IN LONG*/
public static long gcd(long x,long y)
{
    if(x%y==0)
        return y;
    else
        return gcd(y,x%y);
}
    
    
    
                             /* CHECK FOR THE GCD IN INT*/
public static int gcd(int x,int y)
{
    if(x%y==0)
        return y;
    else 
        return gcd(y,x%y);
}


                         /*CHECK FOR THE ABSOLUTE IN INT*/
public static int abs(int a,int b)
{
    return (int)Math.abs(a-b);
}



                        /*CHECK FOR THE ABSOLUTE IN LONG*/
public static long abs(long a,long b)
{
    return (long)Math.abs(a-b);
}


                       /*CHECK FOR MAX BETWEEN TWO NUMBERS IN INT*/
public static int max(int a,int b)
{
    if(a>b)
        return a;
    else
        return b;
}



                       /*CHECK FOR MIN BETWEEN TWO NUMBERS IN INT*/
public static int min(int a,int b)
{
    if(a>b)
        return b;
    else 
        return a;
}


                       /*CHECK FOR MAX BETWEEN TWO NUMBERS IN LONG*/
public static long max(long a,long b)
{
    if(a>b)
        return a;
    else
        return b;
}

                     /*CHECK FOR MIN BETWEEN TWO NUMBERS IN LONG*/
public static long min(long a,long b)
{
    if(a>b)
        return b;
    else 
        return a;
}
                    /*check for power of two of any num*/
static boolean isPowerOfTwo (long v) {
    return (v & (v - 1)) == 0;
}
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;
}

                    /*SORT GIVEN ARRAY*/
static long sort(int a[],int n)
{   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;  }


    
    
                       /*REMOVE ZERO FROM GIVEN NUM*/
static int removeZero(int num) {
        int ret = 0;
        int ten = 1;
        while (num>0) {
                int dig = num % 10;
                num /= 10;
                if (dig>0) {
                        ret += dig * ten;
                        ten *= 10;
                }
        }
        return ret;
}
                 /*CHECK FOR LCM*/
 static int lcm(int x, int y)
    {
        int a;
        a = (x > y) ? x : y; // a is greater number
        while(true)
        {
            if(a % x == 0 && a % y == 0)
                return a;
            ++a;
        }	
    }
}