```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 ; T > 0; T-- {
		var n int
		var a, b, c string
		fmt.Fscan(in, &n, &a, &b, &c)

		ok := false
		for i := 0; i < n; i++ {
			ai, bi, ci := a[i], b[i], c[i]
			if ai == bi {
				if ci != ai {
					ok = true
					break
				}
			} else {
				if ci != ai && ci != bi {
					ok = true
					break
				}
			}
		}

		if ok {
			fmt.Fprintln(out, "YES")
		} else {
			fmt.Fprintln(out, "NO")
		}
	}
}
```