write a go solution for Description:
There is a sheet of paper that can be represented with a grid of size nxm: n rows and m columns of cells. All cells are colored in white initially.

q operations have been applied to the sheet. The i-th of them can be described as follows:

- x_i y_i — choose one of k non-white colors and color the entire row x_i and the entire column y_i in it. The new color is applied to each cell, regardless of whether the cell was colored before the operation.

The sheet after applying all q operations is called a coloring. Two colorings are different if there exists at least one cell that is colored in different colors.

How many different colorings are there? Print the number modulo 998,244,353.

Input Format:
The first line contains a single integer t (1<=t<=10^4) — the number of testcases.

The first line of the testcase contains four integers n,m,k and q (1<=n,m,k,q<=2*10^5) — the size of the sheet, the number of non-white colors and the number of operations.

The i-th of the following q lines contains a description of the i-th operation — two integers x_i and y_i (1<=x_i<=n; 1<=y_i<=m) — the row and the column the operation is applied to.

The sum of q over all testcases doesn't exceed 2*10^5.

Output Format:
For each testcase, print a single integer — the number of different colorings modulo 998,244,353.

Note:
None. Output only the code with no comments, explanation, or additional text.