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.Scanner;

public class Main {
	
	static boolean[] primes;
	static int call=0;
	
	static void primeSet(final int MAX){
		if(call>=MAX){
			return;
		}
		primes = new boolean[MAX+1];
		primes[2] = true;
		for(int i=3;i<=MAX;i+=2){
			primes[i] = true;
		}
		int rt = (int) Math.sqrt(MAX);
		for(int i=3;i<=rt;i+=2){
			if(primes[i]){
				for(int j=i*2;j<=MAX;j+=i){
					primes[j] = false;
				}
			}
		}
	}

	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);

		while(true){

			int n = stdIn.nextInt();
			
			if(n==0)
				return;
			
			primeSet(n+100);

			int a=0;
			for(int i=n;;i--){
				if(primes[i]){
					a=i;
					break;
				}
			}
			for(int i=n;;i++){
				if(primes[i]){
					System.out.println(i-a);
					break;
				}
			}
		}
	}
}