fn main() {
    println!("Hello, world!");
}

struct Solution;

impl Solution {
    pub fn freq_alphabets(mut s: String) -> String {
        for i in 10..=26 {
            let mut integer_str = i.to_string();
            integer_str.push_str("#");
            s = s.replace(&integer_str, &char::from_u32(96 + i).unwrap().to_string() );
        }
        for i in 1..=9 {
            let integer_str = i.to_string();
            s = s.replace(&integer_str, &char::from_u32(96 + i).unwrap().to_string() );
        }
        let i = s.chars().rev();
        i.map(|x| if x == '#' {i.take()})
        s
    }
}