CF1338A.Powered Addition

You have an array $a$ of length $n$. For every positive integer $x$ you are going to perform the following operation during the $x$-th second:

• Select some distinct indices $i_{1}, i_{2}, \ldots, i_{k}$ which are between $1$ and $n$ inclusive, and add $2^{x-1}$ to each corresponding position of $a$. Formally, $a_{i_{j}} := a_{i_{j}} + 2^{x-1}$ for $j = 1, 2, \ldots, k$. Note that you are allowed to not select any indices at all.

You have to make $a$ nondecreasing as fast as possible. Find the smallest number $T$ such that you can make the array nondecreasing after at most $T$ seconds.

Array $a$ is nondecreasing if and only if $a_{1} \le a_{2} \le \ldots \le a_{n}$.

You have to answer $t$ independent test cases.

你有一个长度为 $n$ 的数组 $a$。对于每个正整数 $x$，你将在第 $x$ 秒执行以下操作：

• 选择若干互不相同的下标 $i_{1}, i_{2}, \ldots, i_{k}$，其中每个下标均在 $1$ 到 $n$ 之间（含端点），并对数组 $a$ 中这些位置的元素各加上 $2^{x-1}$。形式化地，对每个 $j = 1, 2, \ldots, k$，执行 $a_{i_{j}} := a_{i_{j}} + 2^{x-1}$。注意：你也可以不选择任何下标（即 $k = 0$）。

你需要尽快使数组 $a$ 变为非递减序列。请找出最小的整数 $T$，使得你能在至多 $T$ 秒内将该数组变为非递减序列。

数组 $a$ 是非递减的，当且仅当满足 $a_{1} \le a_{2} \le \ldots \le a_{n}$。

你需要回答 $t$ 个相互独立的测试用例。

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

The first line of each test case contains single integer $n$ ($1 \le n \le 10^{5}$) — the length of array $a$. It is guaranteed that the sum of values of $n$ over all test cases in the input does not exceed $10^{5}$.

The second line of each test case contains $n$ integers $a_{1}, a_{2}, \ldots, a_{n}$ ($-10^{9} \le a_{i} \le 10^{9}$).

第一行包含一个整数 $t$（$1 \le t \le 10^{4}$）—— 测试用例的数量。

每个测试用例的第一行包含一个整数 $n$（$1 \le n \le 10^{5}$）—— 数组 $a$ 的长度。保证输入中所有测试用例的 $n$ 值之和不超过 $10^{5}$。

每个测试用例的第二行包含 $n$ 个整数 $a_{1}, a_{2}, \ldots, a_{n}$（$-10^{9} \le a_{i} \le 10^{9}$）。

For each test case, print the minimum number of seconds in which you can make $a$ nondecreasing.

对于每个测试用例，输出使 $a$ 变为非递减序列所需的最少秒数。

In the first test case, if you select indices $3, 4$ at the $1$-st second and $4$ at the $2$-nd second, then $a$ will become $[1, 7, 7, 8]$. There are some other possible ways to make $a$ nondecreasing in $2$ seconds, but you can't do it faster.

In the second test case, $a$ is already nondecreasing, so answer is $0$.

In the third test case, if you do nothing at first $2$ seconds and select index $2$ at the $3$-rd second, $a$ will become $[0, 0]$.

在第一个测试用例中，若你在第 $1$ 秒选择下标 $3, 4$，并在第 $2$ 秒选择下标 $4$，则数组 $a$ 将变为 $[1, 7, 7, 8]$。还有其他一些在 $2$ 秒内使 $a$ 变为非递减数组的方法，但无法更快完成。

在第二个测试用例中，$a$ 已经是非递减的，因此答案为 $0$。

在第三个测试用例中，若你在前 $2$ 秒什么都不做，并在第 $3$ 秒选择下标 $2$，则 $a$ 将变为 $[0, 0]$。