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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

import static java.lang.Integer.parseInt;

/**
 * Problem B: Prime Gap
 */
public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line;

		boolean[] ps = new boolean[1299709 + 1];

		Arrays.fill(ps, 2, ps.length, true);

		for (int i = 2; i <= Math.sqrt(ps.length); i++) {
			if (ps[i]) {
				for (int j = i * 2; j < ps.length; j += i) {
					if (ps[j]) ps[j] = false;
				}
			}
		}

		while ((line = br.readLine()) != null && !line.isEmpty()) {

			int k = parseInt(line);
			if (k == 0) break;

			int from = 0, to = 0;
			if (!ps[k]) {
				// from
				for (int i = k; ; i--) {
					if (ps[i]) {
						from = i;
						break;
					}
				}
				// to
				for (int i = k; ; i++) {
					if (ps[i]) {
						to = i;
						break;
					}
				}
			}
			System.out.println(to - from);

		} //end while
	} //end main
}