/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	static class TrieNode {
		boolean isEow;
		TrieNode children[];
		TrieNode() {
			children=new TrieNode[26];
		}
	}
	static class TrieFunctions {
		private TrieNode insert(TrieNode r,int idx,char w[]) {
			if(r==null) {
				r=new TrieNode();
			}
			if (idx == w.length) {
        		r.isEow = true;
        		return r;
		    }
			char ch=w[idx];
			r.children[ch-'a']=insert(r.children[ch-'a'],idx+1,w);
			return r;
		}
		void insert(TrieNode r,char w[]) {
			r=insert(r,0,w);
		}
		private void print(TrieNode r, String word) {
            if (r.isEow)
                System.out.println(word);
 
            for (int i = 0; i < 26; i++) {
                if (r.children[i] != null) {
                    print(r.children[i], word + (char) (i + 'a'));
                }
            }
        }
 
        void printAllWords(TrieNode r) {
            print(r, "");
        }
	}
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		while(t-- != 0){
			TrieNode r = new TrieNode();
			TrieFunctions tf = new TrieFunctions();
			int n = sc.nextInt();
			while(n-- != 0){
				String s = sc.next();
				tf.insert(r, s.toCharArray());
			}
			tf.printAllWords(r);
		}
	}
}

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

MgoxMAphcHAKZG9nCmZsbGV2CmR4bwpkeG8KZHhvCmxyaQpscmkKbHJpCmR4bwo0CmdrdWkKbnlmCm9weXV5CnRhZHk=

2
10
app
dog
fllev
dxo
dxo
dxo
lri
lri
lri
dxo
4
gkui
nyf
opyuy
tady