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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//Author: Mo Abjal, MJP Rohilkhand University Bareilly, UP, India 2018.
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/////////////////////////////*     SOLUTION     *//////////////////////////////
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import java.util.*;
import java.io.*;
import java.text.*;
import java.math.*;
public class Main{
	public static StringTokenizer token = new StringTokenizer("");
	public static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	public static PrintWriter output = new PrintWriter(System.out);
	public static void main(String[] afzal) throws Exception {	
		int R = ni(); int a = ni(); int b = ni(); int c = ni(); int d = ni();
		int x = Math.abs(c-a); 
		int y = Math.abs(d-b);
		double ans = Math.sqrt(Math.pow(x,2)+Math.pow(y,2));
		ans/=2*R;
		output.println((int)Math.ceil(ans));
		output.close(); 
	}
	public String pc(char c){
		return Character.toString(c);
	} 
	public static Integer pi(String str){
		return Integer.parseInt(str);
	}
	public static Long pl(String str){
		return Long.parseLong(str);
	}
	public static String ps(Integer N){
		return Integer.toString(N);
	}
	public static char[] pcc(String str){
		return str.toCharArray();
	}
	public static Integer ni() throws IOException{
		if(!token.hasMoreElements()){
			token = new StringTokenizer(br.readLine());
		}
		return Integer.parseInt(token.nextToken());
	}
	public static Long nl() throws IOException{
		if(!token.hasMoreElements()){
			token = new StringTokenizer(br.readLine());
		}
		return Long.parseLong(token.nextToken());
	}
	public static String ns() throws IOException{
		return new StringTokenizer(br.readLine()).nextToken();
	}
	public static Integer[] ai(int N) throws IOException{
		Integer A[] = new Integer[N];
		token = new StringTokenizer(br.readLine());
		for(int i=0;i<A.length;i++){
			A[i] = pi(token.nextToken());
		}
		return A;
	}
	public static long[] al(int N) throws IOException{
		long A[] = new long[N];
		token = new StringTokenizer(br.readLine());
		for(int i=0;i<N;i++){
			A[i] = Long.parseLong(token.nextToken());
		}
		return A;
	}
	public static char[][] acc(int N,int M) throws IOException{
		char C[][] = new char[N][M];
		for(int i=0;i<N;i++){
			token = new StringTokenizer(br.readLine());
			String s = token.nextToken();
			for(int j=0;j<M;j++){
				C[i][j] = s.charAt(j);
			}
		}
		return C;
	}
	public static String[] as(int N) throws IOException{
		String S[] = new String[N];
		token = new StringTokenizer(br.readLine());
		for(int i=0;i<S.length;i++){
			S[i] = token.nextToken();
		}
		return S;
	}

	public static long fact(long N){
		long fact = 1;
		for(int i=1;i<=N;i++){
			fact = fact * i;
		}
		return fact;
	}
	public static BigInteger factB(int N){
		BigInteger b = new BigInteger("1");
		for(int i=1;i<=N;i++){
			b = b.multiply(BigInteger.valueOf(i));
		}
		return b;
	}
	public static long sod(long N){
		long sum = 0;
		while(N>0){
			long x = N%10;
			sum = sum + x;
			N = N/10;
		}
		return sum;
	}
	public static Integer cd(long N){
		int count=0;
		while(N>0){
			N = N/10; count++;
		}
		return count=0;
	}
}
class Pair implements Comparable{
	int a,b;
	public Pair(int a,int b){
		this.a = a;
		this.b = b;
	}
	public int compareTo(Object p){
		Pair pa = (Pair)p;
		if(this.a==pa.a) return this.b - pa.b;
		return this.a - pa.a;
	} 
}
//Copyright Reserved - Mo Abjal.