fn main() {
    unsafe {
        solve();
    }
}

#[target_feature(enable = "avx2")]
unsafe fn solve() {
    input! {
        w: usize,
        n: usize,
        a: [usize; n],
    }
    let mut f = vec![0u32; w + 1];
    for a in a {
        if a <= w {
            f[a] = !0;
        }
    }
    let mut dp = vec![0u32; w + 1];
    dp[0] = 1;
    const MOD: u32 = 1_000_000_007;
    for i in 0..w {
        let v = dp[i];
        for (dp, f) in dp[(i + 1)..].iter_mut().zip(f[1..].iter()) {
            *dp += v & *f;
            if *dp >= MOD {
                *dp -= MOD;
            }
        }
    }
    println!("{}", dp[w]);
}

// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[macro_export]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[macro_export]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[macro_export]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------