// Space, hyphen and mixed case does not matter
	input = strings.ReplaceAll(input, " ", "")
	input = strings.ReplaceAll(input, "-", "")

	// mixed case does not matter

		if _, found := used[ch]; found {

		// skip spaces and hyphens, because they do not matter
		if ch == ' ' || ch == '-' {
			continue
		}
		if used[ch] {