#ifndef INCLUDED_MAIN
#define INCLUDED_MAIN

#include __FILE__

int main(void){
    int n, m; cin >> n >> m;
    vector<ll> u(n,0), t(m,0);
    int i;
    rep(i,n) cin>> u[i];
    rep(i,m) cin>> t[i];

    // vector<ll> tt; tt.reserve(1e6);
    set<ll> s; s.insert(0);
    rep(i,m){
        queue<ll> q;
        for(auto c : s){
            q.push(c+t[i]);
        }
        while(!q.empty()){
            s.insert(q.front());
            q.pop();
        }
    }

    set<ll> a;
    rep(i,n){
        for(auto c : s){
            a.insert(u[i] + c);
        }
    }
    cout << a.size() << "\n";
}

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

using ll = long long;
using ld=  long double;
#define rep(i,n) for(i=0;i<(n);i++)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()

int randint(int a, int b){
    static mt19937 gen(chrono::steady_clock::now().time_since_epoch().count());
    uniform_int_distribution<int> dist(a,b);
    return dist(gen);
}

namespace nskr{
    template <int id = 0>
    struct modint{
        int v;

        static int& MOD(){
            static int mod = 998244353;
            return mod;
        }

        static int get_mod() { return MOD(); }
        static void set_mod(int m) { MOD() = m; }

        modint() :v(0){}
        modint(long long x) : v( (x>=0 ? x%MOD() : (x%MOD() + MOD()))){}

        long long val() const {return v;}

        modint& operator+=(const modint& x){if((v+=x.v) >= MOD()) v-=MOD(); return *this; }
        modint& operator-=(const modint& x){if((v-=x.v) <  0  ) v+=MOD(); return *this; }
        modint& operator*=(const modint& x){v = (int)(1ll * v * x.v % MOD()); return *this;}
        modint& operator/=(const modint& x){v = (int)(1ll * v * x.inv().val() % MOD()); return *this;}

        modint operator-() const {return modint(-v);}
        modint operator+() const {return *this;}

        modint operator+(const modint& x) const {return modint(*this)+=x;}
        modint operator-(const modint& x) const {return modint(*this)-=x;}
        modint operator*(const modint& x) const {return modint(*this)*=x;}
        modint operator/(const modint& x) const {return modint(*this)/=x;}

        bool operator== (const modint& x) const {return v==x.v;}
        bool operator!= (const modint& x) const {return v!=x.v;}

        friend ostream &operator<<(ostream &os, const modint &p) { return os << p.v; }

        friend istream &operator>>(istream &is, modint &a) {
            int t;
            is >> t;
            a = modint<id>(t);
            return (is);
        }


        modint pow(unsigned long long n) const { 
            modint ret(1), mul(v);
            while(n){
                if(n&1) ret *= mul;
                mul *= mul;
                n >>=1;
            }
            return ret;
        }

        modint inv() const{ //参考：　https://qiita.com/sesame0224/items/f2ac77c367f588c0d29d
            int a = v, b = MOD(), u = 1, w = 0;
            while(b){
                int t = a/b;                 
                swap(a -= t*b, b);
                swap(u -= t*w, w);
            }
            u%=MOD();
            return(u<0?u+MOD():u);
        }


    };

}



#endif