use proconio::input;
use std::collections::HashSet;

fn main() {
    input! {
    n: usize,
    s: String,
    }

    let mut st = HashSet::new();
    for c in s.chars() {
        if st.contains(&c) {
            println!("Yes");
            return;
        }
        st.insert(c);
    }
    println!("No");
}