int str_sz = strlen(right_strs[pos]);

char *word = right_strs[pos];

cout<<"inserting "<<word<<" with len "<<strlen(right_strs[pos])<<endl;

node *cur = root;

for(int i=0; i<str_sz; i++){

int pos = word[i]-'a';

if(cur->sons[pos]==NULL){

//create

node *t = build_trie();

cur->sons[pos] = t;

}

cur = cur->sons[pos];

}

cur->words+=1;

int str_sz = strlen(left_strs[pos]);

char *word = left_strs[pos];

node *cur = root;

for(int i=0; i<str_sz; i++){

int pos = word[i]-'a';

if(cur->sons[pos] == NULL){

return 0;

}else{

cur = cur->sons[pos];

}

}

int t = cur->words;

cout<<"count is "<<t<<" for "<<left_strs[pos]<<endl;

cur->words-=1;

return t;

ptr = 0;

while(scanf("%s %s",left_strs[ptr], right_strs[ptr])!=EOF){

ptr++;

}

node *root = build_trie();

for(int i=0; i<ptr;i++){

//build the trie using right

add_word(root, i);

}

int sum = 0;

int empty = 1;

for(int i=0; i<ptr; i++){

int res = count_words(root, i);

cout<<"res is "<<res<<endl;

if(res<=0){

sum+=1;

}

empty=0;

}

if(empty){

cout<<"Possible"<<endl;

return 0;

}

if(sum<=1){

cout<<"Possible"<<endl;

}else{

cout<<"Impossible"<<endl;

}

return 0;