source_code: import java.util.Scanner;
  
  public class C_1523 {
  
  	static Scanner input = new Scanner(System.in);
  	static int n;
  
  	public static void main(String[] args) {
  		int t = input.nextInt();
  		for(int test = 0; test < t; test++){
  			n = input.nextInt();
  			int num = input.nextInt();
  			if(num == 1){
  				n--;
  				recur("");
  			}else{
  				System.out.println("ERROR");
  			}
  		}
  	}
  	
  	public static int recur(String before){
  		int num = 1;
  		System.out.println(before + num);
  		while(n > 0){
  			int val = input.nextInt();
  			n--;
  			if(val == 1){
  				val = recur(before + num + ".");
  			}
  			if(val == num + 1){
  				num++;
  				System.out.println(before + num);
  			}else{
  				return val;
  			}
  		}
  		return -1;
  	}
  
  }
  