Alice and Bob begin their day with a quick game. They first choose a starting number X0 ≥ 3 and try to reach one million by the process described below. 

Alice goes first and then they take alternating turns. In the i-th turn, the player whose turn it is selects a prime number smaller than the current number, and announces the smallest multiple of this prime number that is not smaller than the current number.

Formally, he or she selects a prime p < Xi - 1 and then finds the minimum Xi ≥ Xi - 1 such that p divides Xi. Note that if the selected prime p already divides Xi - 1, then the number does not change.

Eve has witnessed the state of the game after two turns. Given X2, help her determine what is the smallest possible starting number X0. Note that the players don't necessarily play optimally. You should consider all possible game evolutions.

Input

The input contains a single integer X2 (4 ≤ X2 ≤ 106). It is guaranteed that the integer X2 is composite, that is, is not prime.

Output

Output a single integer — the minimum possible X0.

Examples

Input

14


Output

6


Input

20


Output

15


Input

8192


Output

8191

Note

In the first test, the smallest possible starting number is X0 = 6. One possible course of the game is as follows: 

  * Alice picks prime 5 and announces X1 = 10
  * Bob picks prime 7 and announces X2 = 14. 



In the second case, let X0 = 15. 

  * Alice picks prime 2 and announces X1 = 16
  * Bob picks prime 5 and announces X2 = 20. 
import java.util.*;
import java.io.*;
import java.math.*;

public class Main

{ 
	 static FastReader sc=new FastReader(); 
	 static int dp[][];
	 static int mod=1000000007;
	 static int MAXN = 1000001;
     
	    static int spf[] = new int[MAXN];
	 
	  public static void main(String[] args)
{
		   PrintWriter out=new PrintWriter(System.out);
		   StringBuffer sb=new StringBuffer("");
		  int ttt=1;
		//ttt =i(); 	
		   
	        outer :while (ttt-- > 0) 
			{
	        	int n=i();
		        

		        sieve();
		        ArrayList<Integer> A[]=new ArrayList[n+1];
		        for(int i=0;i<=n;i++) {
		        	A[i]=new ArrayList<Integer>();
		        }
		        for(int i=1;i<=n;i++) {
		        	int x=i;
		        	 while (x != 1)
		             {
		        		 A[i].add(spf[x]);
		                 x = x / spf[x];
		             }
		        
		        }
		        int min=Integer.MAX_VALUE;
		        int res[]=new int[n+1];
		        Arrays.fill(res, -1);
		        for(int i=0;i<A[n].size();i++) {
		        	int y=A[n].get(i);
		        	int z=n/y;
		        	int p=y*(z-1)+1;
		        	for(int j=p;j<n;j++) {
		        		
		        		for(int k=0;k<A[j].size();k++) {
		        			int a=A[j].get(k);
		        			int yy=j/a;
		        			if(yy==1) {
		        				min=Math.min(a, min);
		        				res[j]=min;
		        				continue;
		        			}
		        			int zz=a*(yy-1)+1;
		        			min=Math.min(zz, min);
		        			res[j]=min;
		        			
		        		}
		        	}
		        	
		        }
		        System.out.println(min);
		        
			}

	     //System.out.println(sb.toString());
		     out.close();
	     
	     
	    //CHECK FOR N=1                    //CHECK FOR M=0
        //CHECK FOR N=1                    //CHECK FOR M=0
       	//CHECK FOR N=1
       	//CHECK FOR N=1
       	//CHECK FOR N=1
		        
		     
    }
	  
	   
	  static void sieve()
	    {
	        spf[1] = 1;
	        for (int i=2; i<MAXN; i++)
	            spf[i] = i;
	       
	        for (int i=4; i<MAXN; i+=2)
	            spf[i] = 2;
	       
	        for (int i=3; i*i<MAXN; i++)
	        {
	            if (spf[i] == i)
	            {
	                for (int j=i*i; j<MAXN; j+=i)
	       
	                    if (spf[j]==j)
	                        spf[j] = i;
	            }
	        }
	    }
	  
	  
	  
	  
	 
static class Pair implements Comparable<Pair>
     {
    	 int x;
    	 int y;
    	 Pair(int x,int y){
    		 this.x=x;
    		 this.y=y;
    	 }
		@Override
		public int compareTo(Pair o) {
			if(this.x>o.x)
				return 1;
			else if(this.x<o.x)
				return -1;
			else {
				if(this.y>o.y)
					return 1;
				else if(this.y<o.y)
					return -1;
				else
					return 0;
			}
		}
	
		
     }

static int[] input(int n) {
	int A[]=new int[n];
	   for(int i=0;i<n;i++) {
		   A[i]=sc.nextInt();
	   }
	   return A;
   }
static long[] inputL(int n) {
	long A[]=new long[n];
	   for(int i=0;i<n;i++) {
		   A[i]=sc.nextLong();
	   }
	   return A;
   }
static String[] inputS(int n) {
	String A[]=new String[n];
	   for(int i=0;i<n;i++) {
		   A[i]=sc.next();
	   }
	   return A;
   }
static long sum(int A[]) {
	long sum=0;
	for(int i : A) {
		sum+=i;
	}
	return sum;
}
static long sum(long A[]) {
	long sum=0;
	for(long i : A) {
		sum+=i;
	}
	return sum;
}
static void reverse(long A[]) {
	int n=A.length;
	long B[]=new long[n];
	for(int i=0;i<n;i++) {
		B[i]=A[n-i-1];
	}
	for(int i=0;i<n;i++)
		A[i]=B[i];
	
}
static void reverse(int A[]) {
	int n=A.length;
	int B[]=new int[n];
	for(int i=0;i<n;i++) {
		B[i]=A[n-i-1];
	}
	for(int i=0;i<n;i++)
		A[i]=B[i];
	
}
static void input(int A[],int B[]) {
	   for(int i=0;i<A.length;i++) {
		   A[i]=sc.nextInt();
		   B[i]=sc.nextInt();
	   }
}
static int[][] input(int n,int m){
	int A[][]=new int[n][m];
	for(int i=0;i<n;i++) {
		for(int j=0;j<m;j++) {
			A[i][j]=i();
		}
	}
	return A;
}
static char[][] charinput(int n,int m){
	char A[][]=new char[n][m];
	for(int i=0;i<n;i++) {
		String s=s();
		for(int j=0;j<m;j++) {
			A[i][j]=s.charAt(j);
		}
	}
	return A;
}
static int max(int A[]) {
	int max=Integer.MIN_VALUE;
	for(int i=0;i<A.length;i++) {
		max=Math.max(max, A[i]);
	}
	return max;
}
static int min(int A[]) {
	int min=Integer.MAX_VALUE;
	for(int i=0;i<A.length;i++) {
		min=Math.min(min, A[i]);
	}
	return min;
}
static long max(long A[]) {
	long max=Long.MIN_VALUE;
	for(int i=0;i<A.length;i++) {
		max=Math.max(max, A[i]);
	}
	return max;
}
static long min(long A[]) {
	long min=Long.MAX_VALUE;
	for(int i=0;i<A.length;i++) {
		min=Math.min(min, A[i]);
	}
	return min;
}
static long [] prefix(long A[]) {
	long p[]=new long[A.length];
	p[0]=A[0];
	for(int i=1;i<A.length;i++)
		p[i]=p[i-1]+A[i];
	return p;
}
static long [] prefix(int A[]) {
	long p[]=new long[A.length];
	p[0]=A[0];
	for(int i=1;i<A.length;i++)
		p[i]=p[i-1]+A[i];
	return p;
}
static long [] suffix(long A[]) {
	long p[]=new long[A.length];
	p[A.length-1]=A[A.length-1];
	for(int i=A.length-2;i>=0;i--)
		p[i]=p[i+1]+A[i];
	return p;
}
static long [] suffix(int A[]) {
	long p[]=new long[A.length];
	p[A.length-1]=A[A.length-1];
	for(int i=A.length-2;i>=0;i--)
		p[i]=p[i+1]+A[i];
	return p;
}
static long power(long x, long y, long p)
{

	if(y==0)
		return 1;
	if(x==0)
		return 0;
    long res = 1;
    x = x % p;

    while (y > 0) {

        if (y % 2 == 1)
            res = (res * x) % p;

        y = y >> 1; 
        x = (x * x) % p;
    }

    return res;
}
static void print(int A[]) {
	for(int i : A) {
		System.out.print(i+" ");
	}
	System.out.println();
}
static void print(long A[]) {
	for(long i : A) {
		System.out.print(i+" ");
	}
	System.out.println();
}
static long mod(long x) {
	  return ((x%mod + mod)%mod);
}
static String reverse(String s) {
	StringBuffer p=new StringBuffer(s);
	p.reverse();
	return p.toString();
}

     static int i() {
    	 return sc.nextInt();
     }
     static String s() {
    	 return sc.next();
     }
     static long l() {
    	 return sc.nextLong();
     }  
     static void sort(int[] A){
        int n = A.length;
        Random rnd = new Random();
        for(int i=0; i<n; ++i){
            int tmp = A[i];
            int randomPos = i + rnd.nextInt(n-i);
            A[i] = A[randomPos];
            A[randomPos] = tmp;
        }
        Arrays.sort(A);
     }
     static void sort(long[] A){
	        int n = A.length;
	        Random rnd = new Random();
	        for(int i=0; i<n; ++i){
	            long tmp = A[i];
	            int randomPos = i + rnd.nextInt(n-i);
	            A[i] = A[randomPos];
	            A[randomPos] = tmp;
	        }
	        Arrays.sort(A);
	     }
  static String sort(String s) {
 	 Character ch[]=new Character[s.length()];
 	 for(int i=0;i<s.length();i++) {
 		 ch[i]=s.charAt(i);
 	 }
 	 Arrays.sort(ch);
 	 StringBuffer st=new StringBuffer("");
 	 for(int i=0;i<s.length();i++) {
 		 st.append(ch[i]);
 	 }
 	 return st.toString();
  }
  static HashMap<Integer,Integer> hash(int A[]){
	  HashMap<Integer,Integer> map=new HashMap<Integer, Integer>();
	  for(int i : A) {
		  if(map.containsKey(i)) {
			  map.put(i, map.get(i)+1);
		  }
		  else {
			  map.put(i, 1);
		  }
	  }
	  return map;
  }
  static TreeMap<Integer,Integer> tree(int A[]){
	  TreeMap<Integer,Integer> map=new TreeMap<Integer, Integer>();
	  for(int i : A) {
		  if(map.containsKey(i)) {
			  map.put(i, map.get(i)+1);
		  }
		  else {
			  map.put(i, 1);
		  }
	  }
	  return map;
  }
     static boolean prime(int n) 
	    { 
	        if (n <= 1) 
	            return false; 
	        if (n <= 3) 
	            return true; 
	        if (n % 2 == 0 || n % 3 == 0) 
	            return false; 
	        double sq=Math.sqrt(n);
	  
	        for (int i = 5; i <= sq; i = i + 6) 
	            if (n % i == 0 || n % (i + 2) == 0) 
	                return false; 
	        return true; 
	    } 
     static boolean prime(long n) 
	    { 
	        if (n <= 1) 
	            return false; 
	        if (n <= 3) 
	            return true; 
	        if (n % 2 == 0 || n % 3 == 0) 
	            return false; 
	        double sq=Math.sqrt(n);
	  
	        for (int i = 5; i <= sq; i = i + 6) 
	            if (n % i == 0 || n % (i + 2) == 0) 
	                return false; 
	        return true; 
	    } 
     static int gcd(int a, int b) 
     { 
         if (a == 0) 
             return b; 
         return gcd(b % a, a); 
     } 
     static long gcd(long a, long b) 
     { 
         if (a == 0) 
             return b; 
         return gcd(b % a, a); 
     } 
     
        
    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; 
        } 
    } 
} 



