CF1426A.Floor Number

Vasya goes to visit his classmate Petya. Vasya knows that Petya's apartment number is $n$.

There is only one entrance in Petya's house and the distribution of apartments is the following: the first floor contains $2$ apartments, every other floor contains $x$ apartments each. Apartments are numbered starting from one, from the first floor. I.e. apartments on the first floor have numbers $1$ and $2$, apartments on the second floor have numbers from $3$ to $(x + 2)$, apartments on the third floor have numbers from $(x + 3)$ to $(2 \cdot x + 2)$, and so on.

Your task is to find the number of floor on which Petya lives. Assume that the house is always high enough to fit at least $n$ apartments.

You have to answer $t$ independent test cases.

瓦西娅去拜访他的同学佩佳。瓦西娅知道佩佳的公寓号是 $n$。

佩佳所住的楼房只有一个入口，公寓分布规则如下：第一层有 $2$ 套公寓，其余每一层均有 $x$ 套公寓。公寓编号从 $1$ 开始，按楼层自下而上顺序编号：即第一层的公寓编号为 $1$ 和 $2$；第二层的公寓编号为 $3$ 至 $(x + 2)$；第三层的公寓编号为 $(x + 3)$ 至 $(2 \cdot x + 2)$；依此类推。

你的任务是找出佩佳所住的楼层号。假设该楼房足够高，总公寓数至少为 $n$。

你需要回答 $t$ 个相互独立的测试用例。

The first line of the input contains one integer $t$ ($1 \le t \le 1000$) — the number of test cases. Then $t$ test cases follow.

The only line of the test case contains two integers $n$ and $x$ ($1 \le n, x \le 1000$) — the number of Petya's apartment and the number of apartments on each floor of the house except the first one (there are two apartments on the first floor).

输入的第一行包含一个整数 $t$（$1 \le t \le 1000$），表示测试用例的数量。接下来是 $t$ 个测试用例。

每个测试用例仅一行，包含两个整数 $n$ 和 $x$（$1 \le n, x \le 1000$），分别表示 Petya 所在公寓的编号，以及除第一层外每层楼的公寓数量（第一层有 2 套公寓）。

For each test case, print the answer: the number of floor on which Petya lives.

对于每个测试用例，输出答案：即佩蒂亚所居住的楼层号。

Consider the first test case of the example: the first floor contains apartments with numbers $1$ and $2$, the second one contains apartments with numbers $3$, $4$ and $5$, the third one contains apartments with numbers $6$, $7$ and $8$. Therefore, Petya lives on the third floor.

In the second test case of the example, Petya lives in the apartment $1$ which is on the first floor.

考虑示例中的第一个测试用例：第一层楼包含编号为 $1$ 和 $2$ 的公寓，第二层楼包含编号为 $3$、$4$ 和 $5$ 的公寓，第三层楼包含编号为 $6$、$7$ 和 $8$ 的公寓。因此，Petya 住在第三层楼。

在示例的第二个测试用例中，Petya 住在编号为 $1$ 的公寓，该公寓位于第一层楼。