#![allow(unused_imports)]
use std::io;
use std::str::FromStr;


#[allow(non_snake_case)]
fn main() {

    let V: Vec<i64> = read_array();
    let N: i64 = V[0];
    let A = V[1];
    let X: Vec<i64> = read_array();

    let mut sum: i64 = 0;
    for x in X {
        sum += x;
    }

    if sum == A * N {
        println!("YES");
    }
    else{
        println!("NO");
    }

}


#[allow(dead_code, unused_must_use)]
fn read<F: FromStr>() -> F {
    let mut line = String::new();
    io::stdin().read_line(&mut line);
    match line.trim().to_string().parse::<F>() {
        Ok(v)  => v,
        Err(_) => panic!("Parse Error")
    }
}

#[allow(dead_code, unused_must_use)]
fn read_array <T: FromStr>() -> Vec<T> {
    let scan = io::stdin();
    let mut line = String::new();
    scan.read_line(&mut line).unwrap();
    line.trim().to_string().split_whitespace().map(
        |x| match x.parse::<T>(){
            Ok(x) => x,
            Err(_) => panic!("Parse Error")
        }
    ).collect()
}