#[macro_export]
macro_rules! setup {
    { mut $input:ident: SplitWhitespace $(,)? } => {
        use std::io::Read;
        let mut buf = String::new();
        std::io::stdin().read_to_string(&mut buf).ok();
        let mut $input = buf.split_whitespace();
    };
}

#[macro_export]
macro_rules! parse_next {
    ($str_iter:expr) => {
        $str_iter.next().unwrap().parse().ok().unwrap()
    };
}

#[allow(unused_imports)]
use std::collections::{HashMap, HashSet, VecDeque};

fn main() {
    setup! { mut input: SplitWhitespace };

    let n: usize = parse_next!(input);
    let a: usize = parse_next!(input);
    let x: Vec<usize> = (0..n).map(|_| parse_next!(input)).collect();

    let ans = match (|| {
        let b = (x.iter().sum::<usize>() as f64) / (n as f64);
        (a as f64) == b
    })() {
        true => "YES",
        false => "NO",
    };

    println!("{}", ans);
}