// ---------- 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 {
        assert!(self.0 > 0);
        self.pow(MOD - 2)
    }
}
// ---------- end ModInt ----------
// ---------- begin Precalc ----------
#[allow(dead_code)]
struct Precalc {
    inv: Vec<ModInt>,
    fact: Vec<ModInt>,
    ifact: Vec<ModInt>,
}

#[allow(dead_code)]
impl Precalc {
    pub fn new(n: usize) -> Precalc {
        let mut inv = vec![ModInt::one(); n + 1];
        let mut fact = vec![ModInt::one(); n + 1];
        let mut ifact = vec![ModInt::one(); n + 1];
        for i in 2..(n + 1) {
            inv[i] = -inv[MOD as usize % i] * ModInt(MOD / i as u32);
            fact[i] = fact[i - 1] * ModInt(i as u32);
            ifact[i] = ifact[i - 1] * inv[i];
        }
        Precalc {
            inv: inv,
            fact: fact,
            ifact: ifact,
        }
    }
    pub fn inv(&self, n: usize) -> ModInt {
        self.inv[n]
    }
    pub fn fact(&self, n: usize) -> ModInt {
        self.fact[n]
    }
    pub fn ifact(&self, n: usize) -> ModInt {
        self.ifact[n]
    }
    pub fn comb(&self, n: usize, k: usize) -> ModInt {
        if k > n {
            return ModInt::zero();
        }
        self.fact[n] * self.ifact[k] * self.ifact[n - k]
    }
}
// ---------- end Precalc ----------
// ---------- begin karatsuba multiplication ----------
fn karatsuba<T>(a: &[T], b: &[T], c: &mut [T], zero: T, buf: &mut [T]) 
where T: std::marker::Copy +
         std::ops::Add<Output = T> +
         std::ops::Sub<Output = T> +
         std::ops::Mul<Output = T> +
{
    assert!(a.len() == b.len());
    let n = a.len();
    if n <= 16 {
        for (i, a) in a.iter().enumerate() {
            for (c, b) in c[i..].iter_mut().zip(b.iter()) {
                *c = *c + *a * *b;
            }
        }
        return;
    }
    if n & 1 == 1 {
        karatsuba(&a[1..], &b[1..], &mut c[2..], zero, buf);
        let x = a[0];
        let y = b[0];
        c[0] = c[0] + x * y;
        for (c, (a, b)) in c[1..].iter_mut().zip(a[1..].iter().zip(b[1..].iter())) {
            *c = *c + x * *b + *a * y;
        }
        return;
    }
    let m = n / 2;
    karatsuba(&a[..m], &b[..m], &mut c[..n], zero, buf);
    karatsuba(&a[m..], &b[m..], &mut c[n..], zero, buf);
    let (x, buf) = buf.split_at_mut(m);
    let (y, buf) = buf.split_at_mut(m);
    let (z, buf) = buf.split_at_mut(n);
    for z in z.iter_mut() {
        *z = zero;
    }
    for (x, (p, q)) in x.iter_mut().zip(a.iter().zip(a[m..].iter())) {
        *x = *p + *q;
    }
    for (y, (p, q)) in y.iter_mut().zip(b.iter().zip(b[m..].iter())) {
        *y = *p + *q;
    }
    karatsuba(x, y, z, zero, buf);
    for (z, (p, q)) in z.iter_mut().zip(c[..n].iter().zip(c[n..].iter())) {
        *z = *z - (*p + *q);
    }
    for (c, z) in c[m..].iter_mut().zip(z.iter()) {
        *c = *c + *z;
    }
}

fn multiply<T>(a: &[T], b: &[T], zero: T) -> Vec<T>
where T: std::marker::Copy +
         std::ops::Add<Output = T> +
         std::ops::Sub<Output = T> +
         std::ops::Mul<Output = T> +
{
    let mut i = 0;
    let mut j = 0;
    let mut ans = vec![zero; a.len() + b.len()];
    let mut buf = vec![zero; 4 * (a.len() + b.len())];
    let mut c = Vec::with_capacity(a.len() + b.len());
    while i < a.len() && j < b.len() {
        let x = a.len() - i;
        let y = b.len() - j;
        let z = std::cmp::min(x, y);
        c.clear();
        c.resize(2 * z, zero);
        karatsuba(&a[i..(i + z)], &b[j..(j + z)], &mut c, zero, &mut buf);
        for (ans, c) in ans[(i + j)..].iter_mut().zip(c.iter()) {
            *ans = *ans + *c;
        }
        if x <= y {
            j += x;
        } else {
            i += y;
        }
    }
    ans.truncate(a.len() + b.len() - 1);
    ans
}
// ---------- end karatsuba multiplication ----------

use std::io::Read;

fn calc(a: &[u32]) -> Vec<ModInt> {
    if a.len() == 0 {
        vec![ModInt::one()]
    } else if a.len() == 1 {
        vec![ModInt::one(), ModInt(a[0])]
    } else {
        let m = a.len() / 2;
        multiply(&calc(&a[..m]), &calc(&a[m..]), ModInt::zero())
    }
}

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 mut cnt = vec![0; n];
    for _ in 0..n {
        let a: usize = it.next().unwrap().parse().unwrap();
        if a < n {
            cnt[a] += 1;
        }
    }
    let mut b = vec![];
    for a in cnt {
        if a > 0 {
            b.push(a);
        }
    }
    let dp = calc(&b);
    let pc = Precalc::new(n);
    let mut ans = ModInt::zero();
    let mut sign = ModInt::one();
    for (i, d) in dp.into_iter().enumerate() {
        ans += sign * pc.fact(n - i) * d;
        sign = -sign;
    }
    println!("{}", ans);
}

fn main() {
    run();
}