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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/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */





import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import static java.lang.System.in;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import static java.util.Collections.list;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import javax.xml.stream.events.Characters;





/**
 *
 * @author george
 */
public class main {
public static boolean isPrime(long n) {
    if(n < 2) return false;
    if(n == 2 || n == 3) return true;
    if(n%2 == 0 || n%3 == 0) return false;
    long sqrtN = (long)Math.sqrt(n)+1;
    for(long i = 6L; i <= sqrtN; i += 6) {
        if(n%(i-1) == 0 || n%(i+1) == 0) return false;
    }
    return true;
}

    private static long f(long l) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

static public class Princess{
 public int rate;public int beauty;public int intellect;public int richness;
 public Princess(int sum,int a,int b,int c){
  this.rate=sum;
  this.beauty=a;
  this.intellect=b;
  this.richness=c;
  }

        @Override
        public String toString() {
            return "Princess{" + "rate=" + rate + ", beauty=" + beauty + ", intellect=" + intellect + ", richness=" + richness + '}';
        }
 
 }
public static boolean contains(final int[] arr, final int key) {
    return Arrays.stream(arr).anyMatch(i -> i == key);
}
 static boolean isSubSequence(String str1, String str2, int m, int n)
    {
       
        if (m == 0) 
            return true;
        if (n == 0) 
            return false;
             
        
        if (str1.charAt(m-1) == str2.charAt(n-1))
            return isSubSequence(str1, str2, m-1, n-1);
 
        
        return isSubSequence(str1, str2, m, n-1);
    }

    static int gcdThing(int a, int b) {
    BigInteger b1 = BigInteger.valueOf(a);
    BigInteger b2 = BigInteger.valueOf(b);
    BigInteger gcd = b1.gcd(b2);
    return gcd.intValue();
}
    public static boolean checkAnagram(String str1, String str2) {
        int i=0;
        for (char c : str1.toCharArray()) {
        i = str2.indexOf(c, i) + 1;
        if (i <= 0) { return false; }
    }
    return true;

}
    /* Amusing Joke 
    String a,b,c;
     a=s.next();b=s.next();c=s.next();
     if((a.length()+b.length())!=c.length()){System.out.print("here");System.out.print("NO");}
     else{
         boolean x= true;
         String agex="";
         if(checkAnagram(a, c)==false){System.out.print("here1");x=false;}
         else{
             char [] g=a.toCharArray();
             Arrays.sort(g);String ge=new String(g);a=ge;
             g=b.toCharArray();Arrays.sort(g);ge=new String(b);b=ge;
             g=c.toCharArray();Arrays.sort(g);ge=new String(c);c=ge;
            if(isSubSequence(a, c, a.length(), c.length())){
                 StringBuilder sb = new StringBuilder(c);String temp="";
                for (int i = 0; i < a.length(); i++) {
                    temp+=a.charAt(i);
                 c.replaceFirst(temp, "");temp="";
                   
                }
            }
            else{x=false;}
            if(isSubSequence(a, c, a.length(), c.length())){
              StringBuilder sb = new StringBuilder(c);
                for (int i = 0; i < b.length(); i++) {
                  String temp="";
                    temp+=b.charAt(i);
                 c.replaceFirst(temp, "");temp="";
                   
                }
            }
            else{x=false;}
            if(c.length()!=0){x=false;}
    }if(x==false){System.out.print("NO");}
    else{System.out.print("YES");}
    }
    */
     /*//t,l,r
      long t,l,r;t=s.nextLong();l=s.nextLong();r=s.nextLong();
      long exp=0;
      // t0·f(l) + t1·f(l + 1) + ... + tr - l·f(r).
        for (int i = 0; i <=r-l; i++) {
            exp+=((long)(Math.pow(t, i)))*f(l+i);
        }
        System.out.print(exp%(1000000007));*/
   public static void main (String []  args) throws IOException 
    {
        Scanner s=new Scanner(System.in);
        // r, x, y, x' y' 
        long r,x,y,xd,yd;
        r=s.nextLong();x=s.nextLong();y=s.nextLong();xd=s.nextLong();yd=s.nextLong();
        double side1=x-xd;double side2=y-yd;
        double hyp=(side1*side1)+(side2*side2);
        hyp=Math.sqrt(hyp);
        double result=Math.ceil((hyp/(2*r)));
        System.out.print((int)result);
    }
}    
  
