CF1604A.Era

Shohag has an integer sequence $a_1, a_2, \ldots, a_n$. He can perform the following operation any number of times (possibly, zero):

• Select any positive integer $k$ (it can be different in different operations).
• Choose any position in the sequence (possibly the beginning or end of the sequence, or in between any two elements) and insert $k$ into the sequence at this position.
• This way, the sequence $a$ changes, and the next operation is performed on this changed sequence.

For example, if $a=[3,3,4]$ and he selects $k = 2$, then after the operation he can obtain one of the sequences $[\underline{2},3,3,4]$, $[3,\underline{2},3,4]$, $[3,3,\underline{2},4]$, or $[3,3,4,\underline{2}]$.

Shohag wants this sequence to satisfy the following condition: for each $1 \le i \le |a|$, $a_i \le i$. Here, $|a|$ denotes the size of $a$.

Help him to find the minimum number of operations that he has to perform to achieve this goal. We can show that under the constraints of the problem it's always possible to achieve this goal in a finite number of operations.

肖哈格有一个整数序列 $a_1, a_2, \ldots, a_n$。他可以执行以下操作任意多次（也可以不执行）：

• 任选一个正整数 $k$（不同操作中 $k$ 的取值可以不同）；
• 在序列中的任意位置（可以是序列开头、结尾，或任意两个元素之间）插入 $k$；
• 此时序列 $a$ 发生变化，后续操作将在该新序列上进行。

例如，若 $a=[3,3,4]$ 且他选择 $k = 2$，则操作后可得到如下序列之一：$[\underline{2},3,3,4]$、$[3,\underline{2},3,4]$、$[3,3,\underline{2},4]$ 或 $[3,3,4,\underline{2}]$。

肖哈格希望最终序列满足如下条件：对每个 $1 \le i \le |a|$，均有 $a_i \le i$。其中 $|a|$ 表示序列 $a$ 的长度。

请帮他求出达成该目标所需的最少操作次数。在本题约束下，可以证明总能在有限次操作内达成该目标。

The first line contains a single integer $t$ ($1 \le t \le 200$) — the number of test cases.

The first line of each test case contains a single integer $n$ ($1 \le n \le 100$) — the initial length of the sequence.

The second line of each test case contains $n$ integers $a_1, a_2, \ldots, a_n$ ($1 \le a_i \le 10^9$) — the elements of the sequence.

第一行包含一个整数 $t$（$1 \le t \le 200$）—— 测试用例的数量。

每个测试用例的第一行包含一个整数 $n$（$1 \le n \le 100$）—— 序列的初始长度。

每个测试用例的第二行包含 $n$ 个整数 $a_1, a_2, \ldots, a_n$（$1 \le a_i \le 10^9$）—— 序列的元素。

For each test case, print a single integer — the minimum number of operations needed to perform to achieve the goal mentioned in the statement.

对于每个测试用例，输出一个整数——即为达成题目陈述中所述目标所需的最少操作次数。

In the first test case, we have to perform at least one operation, as $a_2=3 \gt 2$. We can perform the operation $[1, 3, 4] \rightarrow [1, \underline{2}, 3, 4]$ (the newly inserted element is underlined), now the condition is satisfied.

In the second test case, Shohag can perform the following operations:

$[1, 2, 5, 7, 4] \rightarrow [1, 2, \underline{3}, 5, 7, 4] \rightarrow [1, 2, 3, \underline{4}, 5, 7, 4] \rightarrow [1, 2, 3, 4, 5, \underline{3}, 7, 4]$.

In the third test case, the sequence already satisfies the condition.

在第一个测试用例中，我们必须至少执行一次操作，因为 $a_2=3 \gt 2$。我们可以执行操作 $[1, 3, 4] \rightarrow [1, \underline{2}, 3, 4]$（新插入的元素用下划线标出），此时条件即被满足。

在第二个测试用例中，Shohag 可以执行以下操作：

$[1, 2, 5, 7, 4] \rightarrow [1, 2, \underline{3}, 5, 7, 4] \rightarrow [1, 2, 3, \underline{4}, 5, 7, 4] \rightarrow [1, 2, 3, 4, 5, \underline{3}, 7, 4]$。

在第三个测试用例中，该序列已满足条件。