use std::io;
use std::str;

fn main() {
    let mut scan = UnsafeScanner::new(io::stdin().lock());

    let n = scan.token::<i32>();
    let s = scan.token::<String>();

    let mut freq = [0i32; 26];
    for c in s.chars() {
        let char_idx = (c as u8 - b'A') as usize;
        freq[char_idx] += 1;
    }

    for val in freq {
        if val > 1 {
            println!("Yes");
            return;
        }
    }
    println!("No");
}

// I/O template below

pub struct UnsafeScanner<R> {
    reader: R,
    buf_str: Vec<u8>,
    buf_iter: str::SplitAsciiWhitespace<'static>,
}

impl<R: io::BufRead> UnsafeScanner<R> {
    pub fn new(reader: R) -> Self {
        Self {
            reader,
            buf_str: vec![],
            buf_iter: "".split_ascii_whitespace(),
        }
    }

    pub fn token<T: str::FromStr>(&mut self) -> T {
        loop {
            if let Some(token) = self.buf_iter.next() {
                return token.parse().ok().expect("Failed parse");
            }
            self.buf_str.clear();
            self.reader
                .read_until(b'\n', &mut self.buf_str)
                .expect("Failed read");
            self.buf_iter = unsafe {
                let slice = str::from_utf8_unchecked(&self.buf_str);
                std::mem::transmute(slice.split_ascii_whitespace())
            }
        }
    }
}