The sequence of n - 1 consecutive composite numbers (positive integers that are not prime and not equal to 1) lying between two successive prime numbers p and p + n is called a prime gap of length n. For example, (24, 25, 26, 27, 28) between 23 and 29 is a prime gap of length 6.

Your mission is to write a program to calculate, for a given positive integer k, the length of the prime gap that contains k. For convenience, the length is considered 0 in case no prime gap contains k.



Input

The input is a sequence of lines each of which contains a single positive integer. Each positive integer is greater than 1 and less than or equal to the 100000th prime number, which is 1299709. The end of the input is indicated by a line containing a single zero.

Output

The output should be composed of lines each of which contains a single non-negative integer. It is the length of the prime gap that contains the corresponding positive integer in the input if it is a composite number, or 0 otherwise. No other characters should occur in the output.

Example

Input

10
11
27
2
492170
0


Output

4
0
6
0
114
import java.util.Arrays;
import java.util.Scanner;

public class Main 
{
	public static void main(String arg[])
	{
		Scanner sc = new Scanner(System.in);
		int N=1299709;
		boolean a[] = new boolean[N+1];
		Arrays.fill(a, true);
		a[0]=a[1]=false;
		for(int i=2; i*i<=N; i++)
		{
			if(!a[i])
				continue;
			for(int j=i*2; j<=N; j+=i)
			{
				a[j]=false;
			}
		}
	
		while(sc.hasNext())
		{
			int n=sc.nextInt();
			if(n==0)
				return;
			if(a[n]||n==1)
			{
			System.out.println(0);	
				continue;
			}
			int ans=0;
			
			for(int i=n+1; i<=N; i++)
			{
				if(!a[i])
					ans++;
				else
				{
					ans++;
					break;
				}
			}
			for(int i=n-1; i>=0; i--)
			{
				if(!a[i])
					ans++;
				else
				{
					ans++;
					break;
				}
			}
			System.out.println(ans);
		}
	}
}