#include <bits/stdc++.h>
//#include <chrono>
#pragma GCC optimize("Ofast")
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()
#define fi first
#define se second
typedef long long ll;
typedef vector<ll> vec;
typedef vector<vec> mat;

ll N,M,H,W,Q,K,A,B;
string S;
typedef pair<ll, ll> P;
const ll INF = (1LL<<58);

class mint{
    public:
        ll x;
        static unsigned long long mod;
        static unsigned long long mod_plus;
        mint(){x = 0;}
        mint(ll _x) : x((_x < 0 ? ((_x += mod_plus) < 0 ? _x + mod_plus : _x) : _x)%mod){}
        /*mint& operator=(const ll &a){
            x = a;
            return *this;
        }*/

        mint operator-(){
            return x == 0 ? 0 : mod - x;
        }
        mint& operator+=(const mint& a){
            if((x += a.x) >= mod) x -= mod;
            return *this;
        }
        mint operator+(const mint& a) const{
            mint res(*this);
            return res += a;
        }
        mint& operator-=(const mint& a){
            if((x -= a.x) < 0) x += mod;
            return *this;
        }
        mint operator-(const mint& a) const{
            mint res(*this);
            return res -= a;
        }
        mint& operator*=(const mint& a){
            (x *= a.x)%=mod;
            return *this;
        }
        /*mint& operator*=(const ll& a){
            mint temp(a);
            return *this *= temp;
        }*/
        mint operator*(const mint& a) const{
            mint res(*this);
            return res *= a;
        }
        /*mint operator*(const ll& a) const{
            mint res(*this);
            return res *= a;
        }*/
        mint pow(unsigned long long pw) const{
            mint res(1), comp(*this);
            while(pw){
                if(pw&1) res *= comp;
                comp *= comp;
                pw >>= 1;
            }
            return res;
        }
        //以下、modが素数のときのみ
        mint inv() const{
            mint res(*this);
            return res.pow(mod - 2);
        }
        mint& operator/=(const mint &a){
            (x *= a.inv().x)%=mod;
            return *this;
        }
        mint operator/(const mint &a) const{
            mint res(*this);
            return res /= a;
        }
};
ostream& operator<<(ostream& os, const mint& a){
    os << a.x;
    return os;
}
//unsigned long long mint::mod = 998244353;
unsigned long long mint::mod = int(1e+9) + 7;
unsigned long long mint::mod_plus = (LLONG_MAX / mint::mod) * mint::mod;
typedef vector<mint> vm;

ll extgcd(ll a, ll b, ll &x, ll &y){
    ll d = a;
    if(b != 0){
        d = extgcd(b, a%b, y, x);
        y -= (a/b) * x;
    }else{
        x=1;
        y=0;
    }
    return d;
}

int main() {
    cin>>N>>M;
    vec a(N), b(M);
    rep(i,N) cin>>a[i];
    rep(i, M) cin>>b[i];
    mint res(0);
    rep(i, N){
        rep(j, M){
            ll x, y;
            res += (a[i] - 1) * (b[j] + 1) + extgcd(max(a[i], b[j]), min(a[i], b[j]), x, y) + 1;
        }
    }
    cout<<res<<endl;
}