#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N,M; cin >> N >> M;
    vector<int> A(N);
    for(auto &a : A) cin >> a;
    bitset<200001> dp,answer;
    dp.set(0);
    while(M--){
        int t; cin >> t;
        dp |= dp<<t;
    }
    for(auto a : A) answer |= dp<<a;
    cout << answer.count() << endl;
}