#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

trait IteratorExt: Iterator + Sized {
    fn vec(self) -> Vec<Self::Item> {
        self.collect()
    }
}

impl<T: Iterator> IteratorExt for T {}

#[allow(unused)]
use std::cmp::{max, min};
#[allow(unused)]
use std::collections::HashMap;

#[allow(unused)]
fn gcd(x: i64, y: i64) -> i64 {
    if y == 0 {
        x
    } else {
        gcd(y, x % y)
    }
}

#[allow(unused)]
fn lcm(x: i64, y: i64) -> i64 {
    x * y / gcd(x, y)
}

fn main() {
    input! {
        // usize
        // n: usize,
        // vec
        // v: [i64; n],
        n: usize,
        m: usize,
        a: [usize; m],
    }

    let mut floor: Vec<bool> = vec![true; n + 1];
    let mut dp: Vec<i64> = vec![0; n + 1];
    const M: i64 = 1_000_000_007;

    for i in a {
        floor[i] = false;
    }

    dp[0] = 1;
    for i in 1..n + 1 {
        let p1 = if i >= 1 && floor[i - 1] { dp[i - 1] } else { 0 };
        let p2 = if i >= 2 && floor[i - 2] { dp[i - 2] } else { 0 };
        dp[i] = p1 + p2;
    }

    println!("{}", dp[n] % M);
}
