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#17745. K-Good Subsequences

统计

Busy Beaver is too lazy to write an interesting story for this problem, so he just gave you a formal statement.

Define a $M$-sequence as a sequence of positive integers, each between $1$ and $M$ inclusive.

A $M$-sequence is called $K$-good if the absolute difference between any pair of adjacent elements is at most $K$. For example, $[1, 2, 3, 5, 5, 3, 2, 1]$ is $2$-good and $2024$-good, but not $1$-good. We also consider $M$-sequences of length $0$ or $1$ to be $K$-good.

Given positive integers $N$, $M$, $K$, $L$, and a $M$-sequence $a_1, \dots, a_N$ of length $N$, find the maximum possible number of elements in a $M$-sequence $b$, such that:

  • $b$ has $a$ as a prefix; and
  • Every $K$-good subsequence of $b$ has at most $L$ elements.

Recall that a subsequence of a sequence is obtained by deleting some elements (possibly all or none) from a sequence, without reordering the remaining elements.

Input

There are multiple test cases. The first line contains a positive integer $T$ ($1 \le T \le 2 \cdot 10^5$), the number of test cases.

The first line of each test case contains four integers $N$, $M$, $K$, $L$ ($0 \le N \le 2 \cdot 10^5$, $1 \le M \le 10^9$, $0 \le K \le 10^9$, $1 \le L \le 10^9$).

The second line of a test case contains $a_1, \dots, a_N$ ($1 \le a_i \le M$). If $N = 0$, then this line is skipped.

It is guaranteed that every $K$-good subsequence of $a$ has at most $L$ elements. Furthermore, the sum of $N$ over all test cases does not exceed $4 \cdot 10^5$.

Output

For each test case, output one line with the maximum number of elements in $b$. It can be shown that under the problem's constraints, the maximum always exists and does not exceed $9 \cdot 10^{18}$.

Scoring

  • ($5$ points) $M \le K + 1$.
  • ($5$ points) $K = 0$.
  • ($10$ points) $N = 0$.
  • ($15$ points) $N = 1$.
  • ($30$ points) The sum of each of $N$, $M$, $K$, and $L$ over all test cases does not exceed $3000$.
  • ($35$ points) No additional constraints.

Examples

Input 1

3
3 3 1 3
1 3 2
0 5 2 3
7 7 2 3
1 4 2 7 7 1 6

Output 1

5
6
7

Note

In the first sample test case, one possible $M$-sequence $b$ is $[1, 3, 2, 3, 1]$, whose $1$-good subsequences, such as $[3, 2, 3]$ and $[3, 2, 1]$, all have length at most $L = 3$.

In the second sample test case, one possible $M$-sequence $b$ is $[1, 1, 5, 4, 2, 5]$, whose $2$-good subsequences, such as $[5, 4, 2]$ and $[1, 1, 2]$, all have length at most $L = 3$.

In the third sample test case, it can be shown that the only possible $b$ is $b = a$.

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