#include<algorithm>

 #include<iostream>

 #include<cstdlib>

 #include<cstring>

 #include<cstdio>

 const int Max_N = ;

 struct Node{

     int cnt;

     Node *next[];

     inline void set(){

         cnt = ;

         for (int i = ; i < ; i++) next[i] = NULL;

     }

 };

 struct Trie{

     Node stack[Max_N], *root, *tail;

     void init(){

         tail = &stack[];

         root = tail++;

         root->set();

     }

     inline Node *newNode(){

         Node *p = tail++;

         p->set();

         return p;

     }

     inline void insert(Node *x, char *src){

         char *p = src;

         while (*p != '\0'){

             if (!x->next[*p - '']) x->next[*p - ''] = newNode();

             x = x->next[*p - ''];

             x->cnt++;

             p++;

         }

     }

     inline int query(Node *x, char *src){

         char *p = src;

         while (*p != '\0'){

             if (!x || !x->next[*p - '']) return ;

             x = x->next[*p - ''];

             p++;

         }

         return x->cnt;

     }

     inline void insert(char *src){

         insert(root, src);

     }

     inline int query(char *src){

         return query(root, src);

     }

 }trie;

 char ret[][], buf[];

 int main(){

 #ifdef LOCAL

     freopen("in.txt", "r", stdin);

     freopen("out.txt", "w+", stdout);

 #endif

     trie.init();

     int i, n = , k = , flag = ;

     while (~scanf("%s", buf)){

         if ( != strcmp(buf, "")){

             trie.insert(buf);

             strcpy(ret[n++], buf);

         } else if ( == strcmp(buf, "")){

             flag = ;

             for (i = ; i < n; i++){

                 if (trie.query(ret[i]) > ){

                     printf("Set %d is not immediately decodable\n", k++);

                     flag = ;

                     break;

                 }

             }

             if (!flag) printf("Set %d is immediately decodable\n", k++);

             n =  , flag = ;

             trie.init();

         }

     }

     return ;

 }