CF1080B.Margarite and the best present

Little girl Margarita is a big fan of competitive programming. She especially loves problems about arrays and queries on them.

Recently, she was presented with an array $a$ of the size of $10^9$ elements that is filled as follows:

• $a_1 = -1$
• $a_2 = 2$
• $a_3 = -3$
• $a_4 = 4$
• $a_5 = -5$
• And so on ...

That is, the value of the $i$-th element of the array $a$ is calculated using the formula $a_i = i \cdot (-1)^i$.

She immediately came up with $q$ queries on this array. Each query is described with two numbers: $l$ and $r$. The answer to a query is the sum of all the elements of the array at positions from $l$ to $r$ inclusive.

Margarita really wants to know the answer to each of the requests. She doesn't want to count all this manually, but unfortunately, she couldn't write the program that solves the problem either. She has turned to you — the best programmer.

Help her find the answers!

小女孩玛格丽塔是竞技编程的忠实粉丝。她尤其喜欢关于数组及其查询的问题。

最近，她得到了一个大小为 $10^9$ 的数组 $a$，该数组按如下方式填充：

• $a_1 = -1$
• $a_2 = 2$
• $a_3 = -3$
• $a_4 = 4$
• $a_5 = -5$
• 依此类推……

即，数组 $a$ 的第 $i$ 个元素的值由公式 $a_i = i \cdot (-1)^i$ 计算得出。

她立刻针对该数组提出了 $q$ 个查询。每个查询由两个数 $l$ 和 $r$ 描述。查询的答案为数组中从位置 $l$ 到 $r$（含端点）的所有元素之和。

玛格丽塔非常想知道每个查询的答案。她不想手动计算所有结果，但遗憾的是，她自己也无法编写解决该问题的程序。于是她向你——最优秀的程序员——寻求帮助。

请帮她求出所有查询的答案！

The first line contains a single integer $q$ ($1 \le q \le 10^3$) — the number of the queries.

Each of the next $q$ lines contains two integers $l$ and $r$ ($1 \le l \le r \le 10^9$) — the descriptions of the queries.

第一行包含一个整数 $q$（$1 \le q \le 10^3$）—— 表示查询的次数。

接下来的 $q$ 行，每行包含两个整数 $l$ 和 $r$（$1 \le l \le r \le 10^9$）—— 表示每次查询的描述。

Print $q$ lines, each containing one number — the answer to the query.

输出 $q$ 行，每行包含一个数字——对应查询的答案。

In the first query, you need to find the sum of the elements of the array from position $1$ to position $3$. The sum is equal to $a_1 + a_2 + a_3 = -1 + 2 -3 = -2$.

In the second query, you need to find the sum of the elements of the array from position $2$ to position $5$. The sum is equal to $a_2 + a_3 + a_4 + a_5 = 2 -3 + 4 - 5 = -2$.

In the third query, you need to find the sum of the elements of the array from position $5$ to position $5$. The sum is equal to $a_5 = -5$.

In the fourth query, you need to find the sum of the elements of the array from position $4$ to position $4$. The sum is equal to $a_4 = 4$.

In the fifth query, you need to find the sum of the elements of the array from position $2$ to position $3$. The sum is equal to $a_2 + a_3 = 2 - 3 = -1$.

在第一次查询中，你需要计算数组从第 $1$ 个位置到第 $3$ 个位置的所有元素之和。该和为 $a_1 + a_2 + a_3 = -1 + 2 -3 = -2$。

在第二次查询中，你需要计算数组从第 $2$ 个位置到第 $5$ 个位置的所有元素之和。该和为 $a_2 + a_3 + a_4 + a_5 = 2 -3 + 4 - 5 = -2$。

在第三次查询中，你需要计算数组从第 $5$ 个位置到第 $5$ 个位置的所有元素之和。该和为 $a_5 = -5$。

在第四次查询中，你需要计算数组从第 $4$ 个位置到第 $4$ 个位置的所有元素之和。该和为 $a_4 = 4$。

在第五次查询中，你需要计算数组从第 $2$ 个位置到第 $3$ 个位置的所有元素之和。该和为 $a_2 + a_3 = 2 - 3 = -1$。