import java.io.*;
import java.util.*;
import java.math.*;

class Finder {

    int nbTiles;
    int[][] allTiles;
    // ...
    
    public Finder() {
    }

    public void initTiles(String s) {
	String[] lst = s.split(" ");
	nbTiles = Integer.parseInt(lst[0]);
	allTiles = new int[nbTiles][3];
	for(int i=0;i<nbTiles;i++) {
	    allTiles[i][0] = Integer.parseInt(lst[1+3*i]);
	    allTiles[i][1] = Integer.parseInt(lst[1+3*i+1]);
	    allTiles[i][2] = Integer.parseInt(lst[1+3*i+2]);
	}
    }
    

    int getMin() {
	int min = -1;

	/* à compléter */
	return min;
    }
}


class Triominbas {

    public static void main(String[] args) {
	Locale.setDefault(Locale.ENGLISH);

	Finder f = new Finder();

	try {
	    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	    String line = "";
       
	    line = br.readLine();
	    int nb = Integer.parseInt(line);
	    for(int i=0;i<nb;i++) {
		line = br.readLine();
		f.initTiles(line);
		System.out.println(f.getMin());
	    }
	}
	catch(IOException e) {}	
    }
}