#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    constexpr int k = 1e5 + 1;
    vector<int> u(n);
    rep(i, n) cin >> u[i];
    bitset<k> dp;
    dp.set(0);
    rep(i, m) {
        int t;
        cin >> t;
        dp |= dp << t;
    }
    vector<int> v;
    rep(i, k) {
        if (dp[i]) {
            rep(j, n) {
                v.push_back(i + u[j]);
            }
        }
    }
    sort(v.begin(), v.end());
    v.erase(unique(v.begin(), v.end()), v.end());
    cout << v.size() << endl;

    return 0;
}