#include <iostream.h>
#include <string.h>
int set=1;
char get[10][15];
int i,j,k;
int count=1;
void fun() {
  for(i=0;i<count-1;i++) {
   for (j=i+1;j<count;j++) {
    for(k=0;get[i][k]!='\0'&&get[j][k]!='\0';k++) {
	if (get[i][k]!=get[j][k]) break;
	}
	if (get[i][k]=='\0'||get[j][k]=='\0')
	{
  cout<<"Set "<<set++<<" is not immediately decodable"<<endl;
  count=1;
  return;}	
   }
  }
  cout<<"Set "<<set++<<" is immediately decodable"<<endl;
  count=1;
  return;
}
int main() {
  while (cin>>get[0])	{
	for(i=1;;i++)	{
cin>>get[i];
if (strcmp(get[i],"9")==0) break;
count++;}
fun();	}
	return 0;
}