```go
package main

import (
	"bufio"
	"os"
	"strconv"
)

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	writer := bufio.NewWriter(os.Stdout)
	defer writer.Flush()

	scanInt := func() int {
		scanner.Scan()
		val, _ := strconv.Atoi(scanner.Text())
		return val
	}

	if !scanner.Scan() {
		return
	}
	t, _ := strconv.Atoi(scanner.Text())

	for i := 0; i < t; i++ {
		n := scanInt()
		m := scanInt()
		k := scanInt()
		q := scanInt()

		xs := make([]int, q)
		ys := make([]int, q)
		for j := 0; j < q; j++ {
			xs[j] = scanInt()
			ys[j] = scanInt()
		}

		rowSeen := make(map[int]bool)
		colSeen := make(map[int]bool)
		rCnt := 0
		cCnt := 0
		activeOps := 0

		for j := q - 1; j >= 0; j-- {
			x := xs[j]
			y := ys[j]
			rExists := rowSeen[x]
			cExists := colSeen[y]

			isEffective := false
			if !rExists && cCnt < m {
				isEffective = true
			}
			if !cExists && rCnt < n {
				isEffective = true
			}

			if isEffective {
				activeOps++
			}

			if !rExists {
				rowSeen[x] = true
				rCnt++
			}
			if !cExists {
				colSeen[y] = true
				cCnt++
			}
		}

		res := int64(1)
		base := int64(k)
		exp := int64(activeOps)
		mod := int64(998244353)

		for exp > 0 {
			if exp%2 == 1 {
				res = (res * base) % mod
			}
			base = (base * base) % mod
			exp /= 2
		}
		writer.WriteString(strconv.FormatInt(res, 10))
		writer.WriteByte('\n')
	}
}
```