```go
package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	in := bufio.NewReader(os.Stdin)
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	var t int
	fmt.Fscan(in, &t)

	for i := 0; i < t; i++ {
		var n int
		fmt.Fscan(in, &n)
		distinct := make(map[int]struct{})
		for j := 0; j < n; j++ {
			var x int
			fmt.Fscan(in, &x)
			distinct[x] = struct{}{}
		}
		fmt.Fprintln(out, len(distinct))
	}
}
```