6786. Intersection

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int test = sc.nextInt();

        while (test-- > 0) {
            int n = sc.nextInt();

            // 记录最后一辆车和倒数第二辆车的位置
            int x1 = 0, y1 = 0;
            int x2 = 0, y2 = 0;

            // 遍历每一辆车的位置确定最后一辆车和倒数第二辆车的位置
            while (n-- > 0) {
                int x = sc.nextInt();
                int y = sc.nextInt();
                if (y >= y2) {
                    if (x > x2 || y > y2) {
                        x1 = x2;
                        y1 = y2;
                        x2 = x;
                        y2 = y;
                    } else {
                        x1 = x;
                        y1 = y;
                    }
                } else if (y >= y1) {
                    x1 = x > x1 ? x : x1;
                    y1 = y;
                }
            }

            // 根据最后一辆车和倒数第二辆车的位置得出结果
            if (x2 == 2 || (x1 == 2 && y1 == (y2 - 1))) {
                System.out.println(y2 + 2);
            } else {
                System.out.println(y2 + 1);
            }
        }
    }
}