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;

class Main {
    private static int[] calcPrimes(int n) {
        boolean[] table = new boolean[n + 1];
        for (int i = 2; i <= Math.sqrt(n); i++) {
            if (!table[i]) {
                for (int j = i + i; j <= n; j += i) {
                    table[j] = true;
                }
            }
        }
        int counter = 0;
        for (int i = 2; i <= n; i++) {
            if (!table[i]) {
                counter++;
            }
        }
        int[] result = new int[counter];
        int index = 0;
        for (int i = 2; i <= n; i++) {
            if (!table[i]) {
                result[index++] = i;
            }
        }
        return result;
    }

    private static void solve() {
        Scanner scanner = new Scanner(System.in);
        int[] primes = calcPrimes(1299709);

        while (true) {
            int k = scanner.nextInt();
            if (k == 0) {
                break;
            }
            int gap = 0;
            for (int i = 0; i < primes.length; i++) {
                if (primes[i] == k) {
                    gap = 0;
                    break;
                } else if (primes[i] > k) {
                    gap = primes[i] - primes[i - 1];
                    break;
                }
            }
            System.out.println(gap);
        }
    }

    public static void main(String... args) {
        solve();
    }
}