import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;



/**
 *
 * @author kuric10
 */
public class Most {
    
    private static int pocTC,row,min, akt, temp, pom,rozdiel;
    private static int pole[][] = new int[10000002][2];
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)throws  IOException{
        // TODO code application logic here
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        String s,poleS[];
        pocTC = Integer.parseInt(input.readLine());
        
        for (int i = 0; i < pocTC; i++) {
            row = Integer.parseInt(input.readLine());
            min = Integer.MAX_VALUE;
            for (int j = 0; j < row; j++) {
                poleS = input.readLine().split(" ");
                pole[j][0] = Integer.parseInt(poleS[0]);
                pole[j][1] = Integer.parseInt(poleS[1]);
                rozdiel = pole[j][1]-pole[j][0];
                if(min>rozdiel){
                    min = rozdiel;
                }
                
            }
            
            for (int j = 0; j < row; j++) {
                //hore
                for (int k = j-1; k >=Math.max(0, j-min-1); k--) {
                    temp = Math.abs(j-k)+Math.abs(pole[j][0]-pole[k][1]);
                  //  System.out.println(Math.abs(pole[j][1]-pole[k][0]));
                  //  System.out.println("hore"+pole[j][0]+" "+pole[j][1]+" - "+pole[k][0]+" "+pole[k][1]+" temp "+temp);
                  //  System.out.println("");
                    if(temp < min){
                        min = temp;
                  //      System.out.println("j "+j+" "+pole[j][0]);
                    }
                }
                //dole
                 for (int k = j+1; k <Math.min(row, j+min+1); k++) {
                    temp = Math.abs(j-k)+Math.abs(pole[j][0]-pole[k][1]);
                  //  System.out.println(Math.abs(pole[j][1]-pole[k][0]));
                  //  System.out.println("dole"+pole[j][0]+" "+pole[j][1]+" - "+pole[k][0]+" "+pole[k][1]+" temp "+temp);
                   //  System.out.println("");
                    if(temp < min){
                        min = temp;
                    }
                }
                
            }
            System.out.println("K prechodu reky je treba "+min+" pontonu.");
        }
        
    }
    
}