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 static java.lang.System.*;

public class Main {

	Scanner sc = new Scanner(in);
	
	int[] eratosthenes(int n) {
		boolean[] dp = new boolean[n+1];
		dp[0] = dp[1] = true;
		List<Integer> prime = new LinkedList<Integer>();
		for (int i = 2; i <= n; i++) {
			if (dp[i]) continue;
			prime.add(i);
			for (int j = i + i; j <= n; j += i) 
				dp[j] = true;
		}
		
		int[] ret = new int[prime.size()];
		int count = 0;
		for (int num : prime)
			ret[count++] = num;
		
		return ret;
	}
	
	boolean isPrime(int n) {
		if (n < 2) return false;
		for (int i = 2; i * i <= n; i++)
			if (n % i == 0) return false;
			
		return true;
	}
	
	void run() {
		int n;
		int[] prime = eratosthenes(1299709);
		while (true) {
			n = sc.nextInt();
			if (n == 0) break;
			
			if (isPrime(n)) {
				out.println(0);
				continue;
			}
			
			int index = 0;
			while (n > prime[index]) index++;
			out.println(prime[index] - prime[index-1]);
		}
	}
	
	public static void main(String[] args) {
		new Main().run();
	}

}