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

#include <vcl.h>
#pragma hdrstop

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

#pragma argsused
#include <iostream>
#include <string>
using namespace std;

int main(int argc, char* argv[])
{
  int cs,s,f,t,j,i;
  string st,str[100];
  cs=0;
  while (cin>>st)
  {
    s=0;
    f=0;
    while (st[0]!='9')
    {
      str[s++]=st;
      if (f==0)
      for (i=0;i<s-1;i++)
      {
        t=st.length();
        if (str[i].length()<t)
          t=str[i].length();

        for (j=0;j<t;j++)
          if (str[i][j]!=st[j])
            break;
        if (j==t)
        {
          f=1;
          break;
        }
      }
      cin>>st;
    }
    cout<<"Set "<<++cs;
    if (f)
      cout<<" is not immediately decodable"<<endl;
    else
      cout<<" is immediately decodable"<<endl;
  }
  return 0;
}
//---------------------------------------------------------------------------