#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

template <u32 M>
struct modint {
    u32 val;
public:
    static modint raw(int v) { modint x; x.val = v; return x; }
    modint() : val(0) {}
    template <class T>
    modint(T v) { ll x = (ll)(v%(ll)(M)); if (x < 0) x += M; val = u32(x); }
    modint(bool v) { val = ((unsigned int)(v) % M); }
    modint& operator++() { val++; if (val == M) val = 0; return *this; }
    modint& operator--() { if (val == 0) val = M; val--; return *this; }
    modint operator++(int) { modint result = *this; ++*this; return result; }
    modint operator--(int) { modint result = *this; --*this; return result; }
    modint& operator+=(const modint& b) { val += b.val; if (val >= M) val -= M; return *this; }
    modint& operator-=(const modint& b) { val -= b.val; if (val >= M) val += M; return *this; }
    modint& operator*=(const modint& b) { u64 z = val; z *= b.val; val = (u32)(z % M); return *this; }
    modint& operator/=(const modint& b) { return *this = *this * b.inv(); }
    modint operator+() const { return *this; }
    modint operator-() const { return modint() - *this; }
    modint pow(long long n) const { modint x = *this, r = 1; while (n) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; }
    modint inv() const { return pow(M-2); }
    friend modint operator+(const modint& a, const modint& b) { return modint(a) += b; }
    friend modint operator-(const modint& a, const modint& b) { return modint(a) -= b; }
    friend modint operator*(const modint& a, const modint& b) { return modint(a) *= b; }
    friend modint operator/(const modint& a, const modint& b) { return modint(a) /= b; }
    friend bool operator==(const modint& a, const modint& b) { return a.val == b.val; }
    friend bool operator!=(const modint& a, const modint& b) { return a.val != b.val; }
};
using mint = modint<MOD>;
class Factorial {
    vector<mint> facts, factinv;
public:
    explicit Factorial(int n) : facts(n+1), factinv(n+1) {
        facts[0] = 1;
        for (int i = 1; i < n+1; ++i) facts[i] = facts[i-1] * mint(i);
        factinv[n] = facts[n].inv();
        for (int i = n-1; i >= 0; --i) factinv[i] = factinv[i+1] * mint(i+1);
    }
    mint fact(int k) const {
        if(k >= 0) return facts[k]; else return factinv[-k];
    }
    mint operator[](const int &k) const {
        if(k >= 0) return facts[k]; else return factinv[-k];
    }
    mint C(int p, int q) const {
        if(q < 0 || p < q) return 0;
        return facts[p] * factinv[q] * factinv[p-q];
    }
    mint P(int p, int q) const {
        if(q < 0 || p < q) return 0;
        return facts[p] * factinv[p-q];
    }
    mint H(int p, int q) const {
        if(p < 0 || q < 0) return 0;
        return q == 0 ? 1 : C(p+q-1, q);
    }
};

struct Prime { // Wheel factorization
    static constexpr int wheel[] = {4, 2, 4, 2, 4, 6, 2, 6},
            wheel2[] = {7, 11, 13, 17, 19, 23, 29, 31},
            wheel_sum[] = {0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7};
    static inline int f(int n){ return (n-1)/30*8 + wheel_sum[(n-1)%30]; }
    static inline int g(int n){ return ((n-1) >> 3)*30 + wheel2[(n-1)&7]; }
    vector<int> primes;

    Prime(int M) {
        primes = {2, 3, 5};
        if(M < 7){
            while(!primes.empty() && M < primes.back()) primes.pop_back();
            return;
        }
        int n = f(M), m = g(n), k = f(int(floor(sqrt(M))));
        primes.reserve(3+max(0, (int)(n/(log(n)-1.12))));
        vector<bool> sieve(n+1, true);
        for (int i = 1; i <= k; ++i) {
            if(sieve[i]){
                ll p = g(i), q = p*p;
                int j = (i-1)&7;
                while(q <= m){
                    sieve[f(q)] = false;
                    q += wheel[j] * p;
                    j = (j+1)&7;
                }
            }
        }
        for (int i = 1; i <= n; ++i) {
            if(sieve[i]) primes.emplace_back(g(i));
        }
    }
};
constexpr int Prime::wheel[], Prime::wheel2[], Prime::wheel_sum[];
Prime p(1000);
template<class T>
void div_transform(vector<T> &a){
    int n = a.size();
    for (auto &&i : p.primes) {
        if(i >= n) break;
        for (int k = (n-1)/i; k > 0; --k) {
            a[k] += a[k*i];
        }
    }
    for (int i = 1; i < n; ++i) a[i] += a[0];
}
template<class T>
void div_itransform(vector<T> &a){
    int n = a.size();
    for (int i = 1; i < n; ++i) a[i] -= a[0];
    for (auto &&i : p.primes) {
        if(i >= n) break;
        for (int k = 1; k*i < n; ++k) {
            a[k] -= a[k*i];
        }
    }
}
int main() {
    int h, w;
    cin >> h >> w;
    Factorial f(h*w);
    mint ans = f.C(h*w, 3) - mint(h)*f.C(w, 3) - mint(w)*f.C(h, 3);
    int sz = max(h, w);
    vector<mint> a(sz), b(sz);
    for (int i = 1; i < h; ++i) a[i] = h-i;
    for (int i = 1; i < w; ++i) b[i] = w-i;
    div_transform(a); div_transform(b);
    for (int i = 0; i < sz; ++i) a[i] *= b[i];
    div_itransform(a);
    for (int i = 1; i < sz; ++i) ans -= a[i]*(i-1)*2;
    cout << ans.val << "\n";
    return 0;
}