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
#include<iostream>
#include<string>
using namespace std;
int main(){
	int n;
	while(true){
		cin>>n;
		if(n==0)
			break;
		int minprime=n;
		while(true){
			bool t=true;
			for(int i=2;i*i<=minprime;i++){
				if(minprime%i==0)
					t=false;
			}
			if(t==true)
				break;
			minprime--;
		}
		int maxprime=n;
		while(true){
			bool t=true;
			for(int i=2;i*i<=maxprime;i++){
				if(maxprime%i==0)
					t=false;
			}
			if(t==true)
				break;
			maxprime++;
		}
		cout<<maxprime-minprime<<endl;
	}
	return 0;
}