fn print_match(possible_match: Option<usize>) {
    match possible_match {
        Some(match_pos) => println!("Found match at pos {}", match_pos),
        None => println!("Did not find any matches")
    }
}

fn main() {
    let s1 = "abcd";
    let s2 = "abab";
    let s3 = "ab";