Any good reason to 5?

If real name is `foo`, we type `fo`:

1 !<= (2 / 3) = 0.666: not matched. But `fo` is the begin of `foo`, so we notice user to `foo`

If real name is `sing-a-song`, we type `song`:

7 !<= (4 / 3) = 1.33333333333: not matched, `song` are not longer than half of real name.

If real name is `go-command`, we type `command`:

3 <= (11 / 3) = 3.66666: matched.

But if we use 5.

3 !<= (11 / 5) = 2.2: not matched

How to give user alternatives, we can only type less than 1 wrong letter.