fn main() {
    let n: usize = read();
    let a: Vec<usize> = read_vec();

    let mut v: Vec<usize> = vec![0; n - 1];
    for i in 0..n - 1 {
        v[a[i] - 1] += 1;
    }

    let mut ans: String = "Yes".to_string();
    for i in 0..n - 1 {
        if v[n - i - 2] > i + 1 {
            ans = "No".to_string();
            break;
        }
    }

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

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
        .map(|e| e.parse().ok().unwrap()).collect()
}