import java.util.Scanner;


public class Most {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int n = Integer.parseInt(sc.nextLine());
		int len = 0;
		
		for (int k = 0; k < n; k++) {
			
			len = Integer.parseInt(sc.nextLine());
			
			int[] leftBanks = new int [len];
			int[] rightBanks = new int [len];

			
			for (int i = 0; i < len; i++) {
				String row = sc.nextLine();
				Scanner sc2 = new Scanner(row);
				leftBanks[i] = sc2.nextInt();
				rightBanks[i] = sc2.nextInt();	

			}
			
			int minD = Integer.MAX_VALUE;
			
			//boolean run = true;
			
			for (int i = 0; i < len ; i++) {
				for (int j = 0; j < len; j++) {
					
					int dif = Math.abs(i - j);
					
					if (dif > minD) {
						//System.out.println(i + " " + j);
						break;
					}
					
					int dist = Math.abs(leftBanks[i] - rightBanks[j]) + dif;
					if (dist < minD) {
						minD = dist;
					}
				}

			}
			
			System.out.println("K prechodu reky je treba " + minD + " pontonu.");
		}

	}

}