fn main() {
    fn x(s: &str) {
        let mut v = vec![('_', 0); 256];
        let l = |c: char| c.to_ascii_lowercase() as usize;
        s.chars().filter(|c| c != &' ').for_each(|c| {
            let i = l(c);
            v[i].0 = c;
            v[i].1 += 1
        });
        v.sort_by(|a, b| {
            if a.1 == b.1 {
                l(a.0).cmp(&l(b.0))
            } else {
                a.1.cmp(&b.1)
            }
        });
        v.iter()
            .filter(|p| p.1 > 0)
            .for_each(|c| print!("{}{}", c.0, c.1));
    }
    let s = "Database Partitions Task";
    x(s);
}