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.*;
import java.awt.geom.*;
public class Main {

	//0041 start
	
	private void doit(){
		Scanner sc = new Scanner(System.in);
		final int MAX = 1299709;
		boolean [] isprime = new boolean[MAX + 1];
		for(int i = 2; i <= MAX; i++){
			isprime[i] = true;
		}
		for(int i = 2; i * i <= MAX; i++){
			if(isprime[i]){
				for(int j = i * 2; j <= MAX; j+= i){
					isprime[j] = false;
				}
			}
		}
		while(true){
			int n = sc.nextInt();
			if(n == 0) break;
			int pre = n;
			int forward = n;
			while(true){
				if(isprime[pre--]) break;
			}
			pre++;
			while(true){
				if(isprime[forward++])break;
			}
			forward--;
			System.out.println(forward-pre);
		}
		
		
	}

	public static void main(String[] args) {
		Main obj = new Main();
		obj.doit();
	}
}