pub mod nayu {
    pub use std::collections::HashSet;
    use std::{error::Error, str::FromStr};

    fn input_raw_string() -> String {
        let mut buf = String::new();
        std::io::stdin().read_line(&mut buf).unwrap();
        buf
    }

    pub fn input_string() -> String {
        input_raw_string().trim().into()
    }

    fn input_values<T>() -> T
    where
        T: FromStr,
        <T as FromStr>::Err: Error,
    {
        let buf = input_raw_string();
        buf.trim().parse().unwrap()
    }

    pub fn input_uint_value() -> u64 {
        input_values()
    }

    pub fn output_ifne_yesno<T: PartialEq<U>, U: PartialEq<T>>(left: T, right: U) {
        println!("{}", if left != right { "Yes" } else { "No" })
    }
}
use nayu::*;

fn main() {
    let n = input_uint_value();
    let s = input_string();

    output_ifne_yesno(n as usize, s.chars().collect::<HashSet<char>>().len());
}