import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.math.*;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */


/**
 *
 * @author jakab4
 */
public class Most {

    /**
     * @param args the command line arguments
     */
      public static void main(String[] args) throws IOException {
     // BufferedReader r = new BufferedReader(new FileReader(new File("C:\\Users\\jakab4\\Documents\\NetBeansProjects\\Most\\src\\vstup.txt")));  
       BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
        int pocet = Integer.valueOf(r.readLine());    
        for(int i=0; i< pocet; i++)
        {
           int vstup = Integer.valueOf(r.readLine());
           int [][] voda = new int[vstup][2];
           StringTokenizer token;
           for(int j=0; j<vstup;j++)
           {
               token = new StringTokenizer(r.readLine()," ");
               voda[j][0] = Integer.valueOf(token.nextToken());
               voda[j][1] = Integer.valueOf(token.nextToken());        
           
        }
           int min = 1000000000;
           int hodnota = 0;
           int n = 0;
           for(int m=0; m < voda.length;m++)
           {
               /*for(int n=0; n < voda.length; n++)
               { if((Math.abs(m-n)) > min){
                   
               }
               else{
                 if(voda[n][1]-voda[m][0] < 0) hodnota = Math.abs(m-n)-1;
                 else hodnota = Math.abs(voda[m][0]-voda[n][1])+Math.abs(m-n);
                 if(hodnota < min) min = hodnota;
               }
               } 
                       */
               int x = 0;
               n =(m - min);
               if(n < 0) n = 0;
               while(true)
               {
                   if(m==0)
                   {
                    if(x == voda.length) break;
                    if(voda[x][1]-voda[0][0] < 0) hodnota = Math.abs(0-x)-1;
                    else hodnota = Math.abs(voda[0][0]-voda[x][1])+Math.abs(0-x);
                    if(hodnota < min) min = hodnota;
                    x++;
                   }
                   else
                   {
                    if(n > (m +min) || n == voda.length) break;
                    if(voda[n][1]-voda[m][0] < 0) hodnota = Math.abs(m-n)-1;
                    else hodnota = Math.abs(voda[m][0]-voda[n][1])+Math.abs(m-n);
                    if(hodnota < min) min = hodnota;
                    
                    n++;
                   }
               }
                       
           }
        System.out.println("K prechodu reky je treba " +(min) +" pontonu." );
    }
    
}
}