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.* ;
import java.io.*;

public class javaTemplate {
	
	static FastReader sc = new FastReader();
	//	static Scanner sc = new Scanner(System.in) ;

	public static void main(String[] args) {
		
		
		double r = sc.nextDouble();
		double x = sc.nextDouble();
		double y = sc.nextDouble();
		double xd = sc.nextDouble();
		double yd = sc.nextDouble();
		
		double count = (Math.sqrt(Math.pow(Math.abs(x-xd), 2) + Math.pow(Math.abs(y-yd), 2)))/(2*r) ;
	
		System.out.println((int)Math.ceil(count));
		
		
	}
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	 
	
	


	
	
//_________________________//Template//_____________________________________________________________________
	
	
		//		FAST I/O
		static class FastReader {
	        BufferedReader br;
	        StringTokenizer st;
	        
	        public FastReader()
	        {
	            br = new BufferedReader(
	                new InputStreamReader(System.in));
	        }
	 
	        String next()
	        {
	            while (st == null || !st.hasMoreElements()) {
	                try {
	                    st = new StringTokenizer(br.readLine());
	                }
	                catch (IOException e) {
	                    e.printStackTrace();
	                }
	            }
	            return st.nextToken();
	        }
	 
	        int nextInt() { return Integer.parseInt(next()); }
	 
	        long nextLong() { return Long.parseLong(next()); }
	 
	        double nextDouble()
	        {
	            return Double.parseDouble(next());
	        }
	 
	        String nextLine()
	        {
	            String str = "";
	            try {
	                str = br.readLine();
	            }
	            catch (IOException e) {
	                e.printStackTrace();
	            }
	            return str;
	        }
		}
	
	
		
		
		
		
		
		
		
		
		
		//		LPS Array
		static void LPSArray(String pat, int M, int lps[]) {
			int i = 1 ;
			int length = 0 ;
			lps[0] = 0 ;
			
			while(i < M) {
				if(pat.charAt(i) == pat.charAt(length)) {
					length ++ ;
					lps[i] = length ;
					i ++ ;
				} else if(length != 0) {
					length = lps[length-1] ;
				} else {
					lps[i] = length ;
					i ++ ;
				}
			}
		}
		
		
		
		//		KMP Search
		static boolean kmpSearch(String pat, String txt) {
			boolean val = false ;
			int M = pat.length() ;
			int N = txt.length() ;
			
			int lps[] = new int[M] ;
			
			int j = 0 ;
			int i = 0 ;
			
			LPSArray(pat,M,lps) ;
			
			while(i < N) {
				if(pat.charAt(j) == txt.charAt(i)) {
					i ++ ;
					j ++ ;
				} else if(j != 0) {
					j = lps[j-1] ;
				} else {
					i ++ ;
				}
				
				if(j == M) {
					 val = true ;
					 j = lps[j-1] ;
				}
			}
			
			return val ;
		}
	
	
		
			
			
		
		
		
		//		Palindrom or Not
		static boolean isPalindrome(String str, int low, int high) {
					
					while (low < high) {
						if (str.charAt(low) != str.charAt(high)) return false;
					 	low++;
					 	high--;
					}
					return true;
				}
	
	
		// Euler Tortient fx
	static int Phi(int n) {
		
		int count = 0 ;
		for(int i = 1 ; i< n ; i++) {
			if(GCD(i,n) == 1) count ++ ;
		}
		return count ;
	}
	
	
	
		// Integer Sort
		static void sort(int[] a) 
		   {
				ArrayList<Integer> l=new ArrayList<>();
				for (int i:a) l.add(i);
				Collections.sort(l);
				for (int i=0; i<a.length; i++) a[i]=l.get(i);
			}
	
		
		
		
		// Long Sort
		static void sort(long[] a) 
		   {
				ArrayList<Long> l=new ArrayList<>();
				for (long i:a) l.add(i);
				Collections.sort(l);
				for (int i=0; i<a.length; i++) a[i]=l.get(i);
			}
	
	
		
		// boolean Value
		static void val(boolean val)
	    {
	       System.out.println(val ? "YES" : "NO");
	       System.out.flush();
	    }
	
	
		
	
		// GCD
		public static int GCD(int a , int b) {
				if(b == 0) return a ;
				
				return GCD(b, a%b) ;
			}
	
		
		
		
		
		
		// sieve
		public static boolean [] sieveofEratosthenes(int n) {
			
			boolean isPrime[] = new boolean[n+1] ;
			Arrays.fill(isPrime, true);
			isPrime[0] = false ;
			isPrime[1] = false ;
			
			for(int i = 2 ; i * i <= n ; i++) {
				
				for(int j = 2 * i ; j<= n ; j+= i) {
					isPrime[j] = false ;
				}
			}
			
			return isPrime ;
		}
		
		
		
		
		// fastPower
		public static long fastPowerModulo(long a, long b, long n) {
			
			long res = 1 ;
			
			while(b > 0) {
			if((b&1) != 0) {
				res = (res * a % n) % n ;
			}
			
			a = (a % n * a % n) % n ;
			b = b >> 1 ;
			}
			
			return res ;
		}
	

}





