const MOD: usize = 1e9 as usize + 7;

fn upper_bound(target: usize, vals: &Vec<usize>) -> usize {
    let mut upper = vals.len();
    let mut lower = 0usize;
    while upper > lower {
        let middle = (upper + lower) / 2;
        if vals[middle] <= target {
            lower = middle+1;
        } else {
            upper = middle;
        }
    }
    upper
}

fn main() {
    let mut nk = String::new();
    std::io::stdin().read_line(&mut nk).ok();
    let nk: Vec<usize> = nk.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nk[0];
    let k = nk[1];
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<usize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let mut lowers = a.iter().filter(|&&v| v <= k/2).copied().collect::<Vec<_>>();
    let mut uppers = a.iter().filter(|&&v| v > k/2).copied().collect::<Vec<_>>();
    if uppers.len() > n/2 || *uppers.iter().max().unwrap_or(&0usize) > k {
        println!("0");
        return;
    }
    lowers.sort();
    uppers.sort();
    uppers.reverse();
    let mut result = 1usize;
    for i in 0..uppers.len() {
        let v = uppers[i];
        let idx = upper_bound(k-v, &lowers);
        if idx <= i {
            println!("0");
            return;
        }
        result *= idx - i;
        result %= MOD;
    }
    for i in (1..lowers.len()-uppers.len()).step_by(2) {
        result *= i;
        result %= MOD;
    }
    println!("{}", result);
}