Cartoons

Description:

Input:

The first line contains single integer $$$t$$$ ($$$1 \le t \le 1000$$$) — the number of test cases. The following are descriptions of the $$$t$$$ test cases.

The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 2000$$$) — the number of cartoons.

In the next $$$n$$$ lines, the cartoons themselves are described, one per line, by a pair of integers $$$a_i$$$, $$$b_i$$$ ($$$1 \le a_i \le b_i \le 10^9$$$) — the first and last airing days for the $$$i$$$-th cartoon.

It is guaranteed that the sum of the values $$$n$$$ for all test cases in the input does not exceed $$$2000$$$.

Output:

Print $$$t$$$ answers to given test cases in the order in which they appear in the input: the $$$i$$$-th answer is such $$$x$$$, that only one cartoon will be airing on day $$$x$$$ or -1 if there are no such days.

Sample Input:

5
1
1 1
3
2 1000000000
2 500000000
500000002 1000000000
3
1 2
3 4
1 4
2
4 11
4 9
3
1 5
10 10
1 5

Sample Output:

1
500000001
-1
10
10

Note:

In the third test case: at day $$$1$$$ and $$$2$$$, first and third cartoons will be airing, and days $$$3$$$ and $$$4$$$, second and third cartoons will be airing. So, there is no day when only one cartoon will be airing.

In the fourth test case, $$$11$$$ is also a possible answer.