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.io.*;
import java.awt.geom.*;
import java.math.*;

public class Main {

	static final Scanner in = new Scanner(System.in);
	static final PrintWriter out = new PrintWriter(System.out,false);
	static boolean debug = false;

	static BitSet ps;

	static BitSet eratosthenes(int m) {
		int n = m + 1;
		BitSet isp = new BitSet();
		if (n < 2) return isp;

		isp.set(2, n, true);

		for (int i=2; i*i<n; i=isp.nextSetBit(i+1)) {
			for (int j=i+i; j<n; j+=i) {
				isp.set(j,false);
			}
		}

		return isp;
	}


	static boolean solve() {
		int n = in.nextInt();
		if (n == 0) return false;

		if (ps.get(n)) {
			out.println("0");
		} else {
			int l = n, r = n;
			while (!ps.get(--l));
			while (!ps.get(++r));
			out.println((r-l));
		}

		return true;
	}

	public static void main(String[] args) {
		debug = args.length > 0;
		long start = System.nanoTime();

		ps = eratosthenes(1300000);

		while(solve());
		out.flush();

		long end = System.nanoTime();
		dump((end - start) / 1000000 + " ms");
		in.close();
		out.close();
	}

	static void dump(Object... o) { if (debug) System.err.println(Arrays.deepToString(o)); }
}