CF1610C.Keshi Is Throwing a Party

Keshi is throwing a party and he wants everybody in the party to be happy.

He has $n$ friends. His $i$-th friend has $i$ dollars.

If you invite the $i$-th friend to the party, he will be happy only if at most $a_i$ people in the party are strictly richer than him and at most $b_i$ people are strictly poorer than him.

Keshi wants to invite as many people as possible. Find the maximum number of people he can invite to the party so that every invited person would be happy.

凯希正在举办一场派对，他希望派对中的每个人都开心。

他有 $n$ 个朋友。他的第 $i$ 个朋友有 $i$ 美元。

如果你邀请第 $i$ 个朋友参加派对，那么他只有在派对中严格比他富有的人至多有 $a_i$ 个、且严格比他穷的人至多有 $b_i$ 个时，才会感到开心。

凯希希望尽可能多地邀请朋友。请找出他最多能邀请多少人参加派对，使得每位被邀请的人都开心。

The first line contains a single integer $t$ $(1\le t\le 10^4)$ — the number of test cases. The description of the test cases follows.

The first line of each test case contains a single integer $n$ $(1\le n\le 2 \cdot 10^5)$ — the number of Keshi's friends.

The $i$-th of the following $n$ lines contains two integers $a_i$ and $b_i$ $(0 \le a_i, b_i \lt n)$.

It is guaranteed that the sum of $n$ over all test cases doesn't exceed $2 \cdot 10^5$.

第一行包含一个整数 $t$（$1\le t\le 10^4$）—— 测试用例的数量。随后是各测试用例的描述。

每个测试用例的第一行包含一个整数 $n$（$1\le n\le 2 \cdot 10^5$）—— Keshi 的朋友数量。

接下来的 $n$ 行中，第 $i$ 行包含两个整数 $a_i$ 和 $b_i$（$0 \le a_i, b_i \lt n$）。

保证所有测试用例的 $n$ 之和不超过 $2 \cdot 10^5$。

For each test case print the maximum number of people Keshi can invite.

对于每个测试用例，输出 Keshi 最多可以邀请的人数。

In the first test case, he invites the first and the second person. If he invites all of them, the third person won't be happy because there will be more than $1$ person poorer than him.

在第一个测试用例中，他邀请了第一个人和第二个人。如果他邀请所有人，第三个人将不会高兴，因为将有超过 $1$ 个比他更穷的人。