```go
package main

import "fmt"

func main() {
	var t int
	fmt.Scan(&t)
	for i := 0; i < t; i++ {
		var n int
		fmt.Scan(&n)
		a := make([]int, n)
		for j := 0; j < n; j++ {
			fmt.Scan(&a[j])
		}
		b := make([]int, n)
		for j := 0; j < n; j++ {
			fmt.Scan(&b[j])
		}
		pos := make([]int, n+1)
		for j := 0; j < n; j++ {
			pos[a[j]] = j + 1
		}
		current_min := 1 << 30
		k := 0
		for m := n - 1; m >= 0; m-- {
			this_pos := pos[b[m]]
			if this_pos >= current_min {
				break
			}
			current_min = this_pos
			k++
		}
		ans := n - k
		fmt.Println(ans)
	}
}
```