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>

using namespace std;

#define PRIMENUM 1299710

//その数は素数かどうか判定する変数
int isPrime[PRIMENUM];

void makePrimeNumber(){

	isPrime[2]=1;
	isPrime[3]=1;

	for(int i=4;i<PRIMENUM;i++){
		int flag=0;
		for(int j=2;j*j<=i;j++){
			if(i%j==0){
				flag=1;
				break;
			}
		}
		if(flag==0){
			isPrime[i]=1;
			//cout<<i<<endl;
		}	
	}

}

int main(){
	int n;

	makePrimeNumber();

	while(cin>>n){
		if(n==0)break;
		if(isPrime[n]==1){
			cout<<0<<endl;
			continue;
		}

		int start,end;

		for(int i=n-1;i>=0;i--){

			if(isPrime[i]==1){
				start = i;
				break;
			}
		}
		for(int i=n+1;i<=PRIMENUM;i++){
			if(isPrime[i]==1){
				end = i;
				break;
			}
		}
		cout<<end-start<<endl;
	}

	return 0;
}