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,n) for(int i=0;i<(n);i++)
#define ALL(v) (v).begin(),(v).end()
#define int long long
typedef pair<int,int> P;

//-----------------------------------------------------------------------

const int SZ=1300000;
bool isPrime[SZ];

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    for(int i=2;i<SZ;i++) isPrime[i]=true;
    for(int i=2;i<SZ;i++){
        if(!isPrime[i]) continue;
        for(int j=2*i;j<SZ;j+=i) isPrime[j]=false;
    }
    
    int n;
    while(cin>>n,n)
    {
        int p1=n,p2=n;
        while(!isPrime[p1]) p1++;
        while(!isPrime[p2]) p2--;
        cout<<p1-p2<<endl;
    }

}

