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;

bool ipn(int n){//cout<<n<<endl;
  if(n == 2 || n == 3) return true;
  if(n <= 4 || n%2 == 0 || n%3 == 0) return false;
  for(int i = 6; (i-1)*(i-1) <= n; i+=6)
    if(n%(i-1) == 0 || n%(i+1) == 0) return false;
  return true;
}

int main(){
  int n, mi, ma;
  while(cin>>n, n){
    for(int i = n;;i++)
      if(ipn(i)){ma=i;break;}
    for(int i = n;;i--)
      if(ipn(i)){mi=i;break;}
    cout<<ma-n + n - mi<<endl;
  }

  return 0;
}
