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<bits/stdc++.h>
using namespace std;
 
#define REP(i,s,n) for(int i=s;i<n;++i)
#define rep(i,n) REP(i,0,n)
#define SORT(c) sort((c).begin(),(c).end())
#define IINF INT_MAX
#define LLINF LLONG_MAX
#define DEBUG false

typedef long long ll;
typedef pair<int, int> ii;

vector<int> prime;

int main() {
	
	vector<bool> use(1299710, false);
	REP(i, 2, 1299710){
		if(!use[i])prime.push_back(i);
		for(int j = 2; i * j <= 1299710; j++) use[i * j] = true;
	}
	
	int n;
	while(cin >> n, n){
		auto it1 = upper_bound(prime.begin(), prime.end(), n);
		auto it2 = lower_bound(prime.begin(), prime.end(), n);
		it1--;
		cout << *it2 - *it1 << endl;
	}
	
	
	return 0;
}