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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.StringTokenizer;


public class Main {

	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskC solver = new TaskC();
		solver.solve(1, in, out);
		out.close();
	}

	static class TaskC {
		static boolean visited[]  ;
		static boolean found = false; 
		static int steps = 0 ;
		static int n ; 
		static int[][] memo ;
		static ArrayList<Integer> p  ;
		public void solve(int testNumber, InputReader in, PrintWriter out) {
			int x = in.nextInt() ; 
			int min = (getPrimes(x)*((x/getPrimes(x))-1))+1 ;
			int max = x ; 

			int res = Integer.MAX_VALUE ;
			for (int i = min; i <= max; i++)
			{
				if(!isPrime(i))
				{
					int minn = (getPrimes(i)*((i/getPrimes(i))-1))+1 ;
					res  = Math.min(minn, res) ;
				}
			}

			System.out.println(res);

		}

		public static int getPrimes(int x ){
			//			for (int i = x-1; i>1; i--)
			//			{
			//				if(x%i==0 && isPrime(i)){
			//					return i ;
			//				}
			//			}
			//			return x ;

			if(isPrime(x))
				return x ;
			for (int i = 2; i*i<=x; i++)
			{
				if(x%i==0 && isPrime(i))
					return getPrimes(x/i) ;
			}
			return -1;
		}
		public static String solve(String x){

			int n = x.length() ; 
			String y = "" ;
			for (int i = 0; i < n-2; i+=2)
			{
				if(ifPalindrome(x.substring(i, i+2)))
					y+= x.substring(i, i+2) ;
				else 
					break ;
			}
			return y+ solve1(x.substring(y.length(),x.length())) ;

		}
		public static String solve1(String x){
			String y = x.substring(0 , x.length()/2) ; 
			return "" ;

		}
		public static String reverse(String x){
			String y ="" ;
			for (int i = 0; i < x.length(); i++)
			{
				y  = x.charAt(i) + y ;
			}
			return y ;
		}

		public static boolean ifPalindrome(String x){
			int numbers[] = new int[10] ; 
			for (int i = 0; i < x.length(); i++)
			{
				int z = Integer.parseInt(x.charAt(i)+"") ; 
				numbers[z] ++ ;
			}
			for (int i = 0; i < numbers.length; i++)
			{
				if(numbers[i]%2!=0)
					return false; 
			}
			return true ;	
		}

		public static int get(int n){
			return n*(n+1)/2 ; 
		}
		//		public static long getSmallestDivisor( long y){
		//			if(isPrime(y))
		//				return -1;
		//
		//			for (long i = 2; i*i <= y; i++)
		//			{
		//				if(y%i ==0)
		//				{
		//					return i;
		//				}
		//			}
		//			return -1;
		//		}
		//		public static void lis(pair []a , int n){
		//			int lis[] = new int[n] ; 
		//			Arrays.fill(lis,1) ; 
		//
		//			for(int i=1;i<n;i++)
		//				for(int j=0 ; j<i; j++)
		//					if (a[i].y>a[j].y &&  lis[i] < lis[j]+1)   
		//						lis[i] = lis[j] + 1;           
		//
		//			int max = lis[0];
		//
		//			for(int i=1; i<n ; i++)
		//				if (max < lis[i])
		//					max = lis[i] ;
		//			System.out.println(max);
		//
		//			ArrayList<Integer> s = new ArrayList<Integer>() ;
		//			for (int i = n-1; i >=0; i--)
		//			{
		//				if(lis[i]==max)
		//				{
		//					s.add(a[i].z);
		//					max --; 
		//				}
		//			}
		//
		//			for (int i = s.size()-1 ; i>=0 ;  i--)
		//			{
		//				System.out.print(s.get(i)+" ");
		//			}
		//
		//			return  ; 
		//		}
		public static int calcDepth(Vertix node){
			if(node.depth>0) return node.depth; 
			// meaning it has been updated before;
			if(node.parent != null)
				return 1+ calcDepth(node.parent);
			else
				return -1;
		}
		public static int helper(int a[] , int i , int j , int d ,  int n){
			if(j==i || i==n-1 || j==0)
				return 0; 
			if(a[j] - a[i] <= d)
				return 0; 
			if(memo[i][j]!= -1)
				return memo[i][j] ; 

			if( a[j-1]-a[i]< a[j]-a[i+1])
				return memo[i][j]=1 + helper(a, i, j-1, d , n) ; 
			if( a[j-1]-a[i]> a[j]-a[i+1])
				return memo[i][j]=1+ helper(a , i+1 , j , d ,n ) ;
			return memo[i][j]=1+ Math.min(helper(a, i, j-1, d , n) , helper(a , i+1 , j , d ,n )) ;

		}
		public static boolean isPrime (int num){
			if (num < 2) return false;
			if (num == 2) return true;
			if (num % 2 == 0) return false;
			for (int i = 3; i * i <= num; i += 2)
				if (num % i == 0) return false;
			return true;
		}

		public static boolean dfs(Vertix v , int target){
			try{
				visited[v.i]= true ;
			} catch (NullPointerException e)
			{
				System.out.println(v.i);
			}
			if(v.i == target)

				return true ;
			for (int i =0 ; i< v.neighbours.size() ; i++)
			{ 

				Vertix child = v.neighbours.get(i) ;
				if(child.i == target){
					found = true  ; 
				}
				if(visited[child.i]==false){
					found |= dfs(child, target) ;
				}
			}
			return found; 
		}






	}
	static class InputReader {
		public BufferedReader reader;
		public StringTokenizer tokenizer;

		public InputReader(InputStream stream) {
			reader = new BufferedReader(new InputStreamReader(stream), 32768);
			tokenizer = null;
		}

		public String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}

		public int nextInt() {
			return Integer.parseInt(next());
		}

	}
	public static class Vertix{
		int i ; 
		int depth ;
		ArrayList<Vertix> neighbours ; 
		Vertix parent ; 

		public Vertix(int i){
			this.i = i ;
			this.neighbours = new ArrayList<Vertix> () ;
			this.parent = null ;
			depth =-1;
		}
	}

	public static class pair implements Comparable<pair>{
		int x ;  // neededLessonsToSkip //k
		int y ;  // value


		public pair(int x, int y){
			this.x=x ; 
			this.y=y ;

		}

		@Override
		public int compareTo(pair p) {
			if(this.x > p.x)
				return 1 ; 
			else if(this.x== p.x)
			{
				if(this.y >= p.y)
					return 1 ;
				else 
					return -1 ;
			}
			else return -1 ;


		}


	}


}