#include <iostream>

int table [100000];

using namespace std;

#include <algorithm>

#include <map>
#include <vector>




int main()
{
  freopen("generate.in","r",stdin);
  
  while(true)
  {
    int n;  
    cin >> n;
    
   for(int i=0;i<10000;i++)table[i]=0;
    
    
    if(n==0) break;
    
    int res =0;
    table[n]=1;
    
    int nf=n;

    
    for(res=1;;res++)
    {
      nf=((nf*nf)/100)%10000;
      if(table[nf])break;
      table[nf]=1;
      
    }
   
    
   // for(int i=0;i<res*2;i++)cout << table[i]<<endl;
    
    
    
    cout << res<<endl;
    
    
    
    
   
  }
  
  
    
}