#ifdef ONLINE_JUDGE
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#endif
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using mint = modint998244353;
using mint2 = modint1000000007;
#define each(a, ...) for(auto& __VA_ARGS__ : a)
#define Each(a, ...) for(auto __VA_ARGS__ : a)
#define sz(a) (ll)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
template<class T, class U> inline bool chmax(T &a, U &&b) { if (a >= (T)b) return false; a = b; return true; }
template<class T, class U> inline bool chmin(T &a, U &&b) { if (a <= (T)b) return false; a = b; return true; }
template<class T, class U> istream &operator>>(istream &is, pair<T, U> &p) { return is >> p.first >> p.second; }
template<class T> requires requires(T t) { begin(t); end(t); } && (!is_same_v<T, string>) istream &operator>>(istream &is, T &v) { for (auto &x : v) is >> x; return is; }
template<class... T> inline void in(T&... a) { (cin >> ... >> a); }
template<class T, class U> ostream &operator<<(ostream &os, const pair<T, U> &p) { return os << p.first << ' ' << p.second; }
template<class T> requires requires(T t) { begin(t); end(t); } && (!is_same_v<T, string>) ostream &operator<<(ostream &os, const T &v) { for (auto it = begin(v); it != end(v); it++) os << (it == begin(v) ? "" : " ") << *it; return os; }
void out() { cout << '\n'; }
template<class T, class... U> inline void out(T &&a, U&&... b) { cout << a; ((cout << ' ' << b), ...); cout << '\n'; }
template<class... T> inline void print(T&&... a) { (cout << ... << a); }
template<class T = string, class U = string> inline bool yn(bool a, T &&b = "Yes", U &&c = "No") { if (a) out(b); else out(c); return a; }
constexpr ll inf = LLONG_MAX >> 2;
constexpr array<pair<ll, ll>, 4> dxdy4 = {{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}};
constexpr array<pair<ll, ll>, 8> dxdy8 = {{{-1, 0}, {-1, -1}, {0, -1}, {1, -1}, {1, 0}, {1, 1}, {0, 1}, {-1, 1}}};

void Main() {
    ll N,M;in(N,M);
    vector<ll>U(N),T(M);in(U,T);
    bitset<200000>bs;
    each(U,Ui)bs[Ui]=1;
    each(T,Ti)bs|=bs<<Ti;
    out(bs.count());
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(20);
    Main();
    cout << flush;
    _Exit(EXIT_SUCCESS);
}