// ---------- begin ModInt ----------
const MOD: u32 = 1_000_000_007;

#[derive(Clone, Copy)]
struct ModInt(u32);

impl std::ops::Add for ModInt {
    type Output = ModInt;
    fn add(self, rhs: ModInt) -> Self::Output {
        let mut d = self.0 + rhs.0;
        if d >= MOD {
            d -= MOD;
        }
        ModInt(d)
    }
}

impl std::ops::AddAssign for ModInt {
    fn add_assign(&mut self, rhs: ModInt) {
        *self = *self + rhs;
    }
}

impl std::ops::Sub for ModInt {
    type Output = ModInt;
    fn sub(self, rhs: ModInt) -> Self::Output {
        let mut d = self.0 + MOD - rhs.0;
        if d >= MOD {
            d -= MOD;
        }
        ModInt(d)
    }
}

impl std::ops::SubAssign for ModInt {
    fn sub_assign(&mut self, rhs: ModInt) {
        *self = *self - rhs;
    }
}

impl std::ops::Mul for ModInt {
    type Output = ModInt;
    fn mul(self, rhs: ModInt) -> Self::Output {
        ModInt((self.0 as u64 * rhs.0 as u64 % MOD as u64) as u32)
    }
}

impl std::ops::MulAssign for ModInt {
    fn mul_assign(&mut self, rhs: ModInt) {
        *self = *self * rhs;
    }
}

impl std::ops::Neg for ModInt {
    type Output = ModInt;
    fn neg(self) -> Self::Output {
        ModInt(if self.0 == 0 {0} else {MOD - self.0})
    }
}

impl std::fmt::Display for ModInt {
    fn fmt<'a>(&self, f: &mut std::fmt::Formatter<'a>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl std::str::FromStr for ModInt {
    type Err = std::num::ParseIntError;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let val = s.parse::<u32>()?;
        Ok(ModInt::new(val))
    }
}

#[allow(dead_code)]
impl ModInt {
    pub fn new(n: u32) -> ModInt {
        ModInt(n % MOD)
    }
    pub fn zero() -> ModInt {
        ModInt(0)
    }
    pub fn one() -> ModInt {
        ModInt(1)
    }
    pub fn pow(self, mut n: u32) -> ModInt {
        let mut t = ModInt::one();
        let mut s = self;
        while n > 0 {
            if n & 1 == 1 {
                t *= s;
            }
            s *= s;
            n >>= 1;
        }
        t
    }
    pub fn inv(self) -> ModInt {
        self.pow(MOD - 2)
    }
}
// ---------- end ModInt ----------

use std::io::Read;

fn run() {
    let mut s = String::new();
    std::io::stdin().read_to_string(&mut s).unwrap();
    let mut it = s.trim().split_whitespace();
    let n: usize = it.next().unwrap().parse().unwrap();
    let x: usize = it.next().unwrap().parse().unwrap();
    let mut a: Vec<usize> = it.map(|s| s.parse().unwrap()).collect();
    a.sort();
    let mut dp = vec![vec![ModInt::zero(); x + 1]; 1];
    dp[0][0] = ModInt::one();
    for (i, a) in a.into_iter().rev().enumerate() {
        let mut next = vec![vec![ModInt::zero(); x + 1]; std::cmp::min(dp.len() + 1, n - i + 1)];
        for (x, dp) in dp.into_iter().enumerate() {
            for (y, v) in dp.into_iter().enumerate() {
                if v.0 == 0 {
                    continue;
                }
                if let Some(p) = next.get_mut(x + 1).and_then(|next| next.get_mut(y + a)) {
                    *p += v;
                }
                if let Some(p) = next.get_mut(x).and_then(|next| next.get_mut(y)) {
                    *p += v * ModInt((y - x * a + x) as u32);
                }
                let u = v * ModInt((2 * x) as u32);
                for d in 1..(a + 1) {
                    if let Some(p) = next.get_mut(x).and_then(|next| next.get_mut(y + d)) {
                        *p += u;
                    }
                }
                if x > 1 {
                    let u = v * ModInt((x * (x - 1)) as u32);
                    let mut add = ModInt::zero();
                    for d in (1..(a + 1)).rev() {
                        add += u;
                        if let Some(p) = next.get_mut(x - 1).and_then(|next| next.get_mut(y + d)) {
                            *p += add;
                        }
                    }
                }
            }
        }
        dp = next;
    }
    let ans = dp[1][x];
    println!("{}", ans);
}

fn main() {
    run();
}


Measured memory_bytes: 4352