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.*;
public class Main {
	static Scanner sc = new Scanner(System.in);
	static boolean[] prime = new boolean[1300000];
	static int n;
	public static void main(String[] args) {
		make_prime();
		while(read()){
			solve();
		}
	}
	
	static boolean read(){
		n = sc.nextInt();
		if(n == 0)return false;
		return true;
	}
	
	static void solve(){
		if(prime[n]){
			System.out.println(0);
		}else{
			int up = 0, down = 0;
			for(int i = n; !prime[i]; i++){
				up++;
			}
			for(int i = n; !prime[i]; i--){
				down++;
			}
			System.out.println(up + down);
		}
	}

	
	static void make_prime(){
		Arrays.fill(prime, true);
		prime[0] = false;
		prime[1] = false;
		for(int i = 2; i < prime.length; i++){
			if(prime[i]){
				for(int j = 2*i; j < prime.length; j += i){
					prime[j] = false;
				}
			}
		}
	}
}