pub fn run(input: String) {
    //let wlen = 4;
    let wlen = 14;
    let (wix, _) = input.chars().collect::<Vec<char>>().windows(wlen).enumerate().find(|(_, win)| {
        //println!("checking window {:?}", win.into_iter().map(|ch|{ch.to_owned()}).collect::<Vec<char>>());
        let n = win.len();
        for i in 0..n {
            for j in i..n {
                if i != j && win[i]==win[j] {
                    return false;
                }
            }
        }
        return true;
    }).expect("no unique sequence!");
    println!("Day 6: {}", wix + wlen);
}