use proconio::input;

const L: usize = 1000010;

fn main(){
    input!{
        n: usize,
        m: usize,
        a: [usize; n],
        b: [usize; m],
    }

    let mut dp = vec![false; L];
    for x in a{
        dp[x] = true;
    }

    for x in b{
        for i in (x..L).rev(){
            if dp[i-x]{
                dp[i] = true;
            }
        }
    }

    let mut ans = 0;
    for i in 0..L{
        ans += if dp[i]{1} else{0};
    }
    println!("{}", ans);
}