#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
// /*
// //////////**DEFINES - START**//////////
#define ret return
#define fi first
#define se second
#define mp make_pair
#define all(x) x.begin(), x.end()
#define be(x) x.begin()
#define en(x) x.end()
#define sz(x) ll(x.size())
#define for0(i, n) for (ll i = 0; i < (n); ++i)
#define for1(i, n) for (ll i = 1; i < (n); ++i)
#define rfor0(i, n) for (ll i = (n) - 1; i >= 0; --i)
#define rfor1(i, n) for (ll i = (n) - 1; i >= 1; --i)
#define rep(i, a, n) for (ll i = a; i < ll(n); ++i)
#define rrep(i, a, n) for (ll i = a - 1; i >= ll(n); --i)
#define popcount __builtin_popcount
#define popcountll __builtin_popcountll
#define fastIO() ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define con continue
#define pb push_back
#define pob pop_back
#define deb(x) cout << (#x) << " is " << (x) << endl
#define ins insert
#define len(s) (s).length()
#define gi greater<int>()
#define gll greater<ll >()
#define gstr greater<string>()
#define gpll greater<pair<ll , ll >>()
#define rast(x1, y1, x2, y2) sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))
#define rev reverse
#define ub upper_bound
#define lb lower_bound
#define bs binary_search
#define rs resize
#define last(a) a.back()
#define co count
#define ba(a) a.back()
#define um unordered_map
#define rsun(a) a.resize(unique(a.begin(), a.end())-a.begin())
#define endl '\n'
#ifdef OG_Matveychick1
bool local = true;
#else
bool local = false;
#endif
// \\\\\\\\\\**DEFINES - END**\\\\\\\\\\
// */
// /*
// //////////**TYPEDEFS - START**//////////
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<char> vc;
typedef pair<int, int> pii;
typedef vector<pii> vpii;
typedef vector<string> vs;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<ull> vull;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;
typedef pair<double, double> pdd;
typedef double ld;
typedef double D;
typedef vector<ld> vld;
typedef vector<pair<ld, ld>>
vpld;
typedef string str;
typedef set<ll> sll;
typedef set<int> si;
typedef set<str> ss;
typedef set<pii> spii;
typedef multiset<int> msi;
typedef multiset<ll> msll;
typedef multiset<str> mss;
typedef multiset<pii> mspii;
typedef multiset<pll> mspll;
typedef map<str, str> mps;
typedef map<int, int> mpi;
typedef map<ll, ll> mpll;
typedef map<int, vi> mpvi;
typedef map<int, vll> mpvll;
typedef map<char, int> mpci;
typedef multimap<ll, ll> mmpll;
typedef multimap<str, str> mmps;
typedef multimap<int, int> mmpi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
typedef vector<vector<long double>> vvld;
typedef vector<vvi> vvvi;
typedef vector<vector<char>> vvc;
typedef vector<vs> vvs;
typedef vector<D> vD;
typedef set<pair<ll, ll>>
spll;
typedef pair<ull, ull> pull;
typedef vector<pull> vpull;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef set<char> sc;
typedef queue<int> qi;
typedef queue<ll> qll;
typedef queue<bool> qb;
typedef vector<sll> vsll;
typedef queue<pair<ll, ll>>
qpll;
typedef vector<vector<pair<int, int>>>
vvpii;
typedef vector<vector<pair<ll, ll>>>
vvpll;
typedef vector<spll> vspll;
typedef multiset<char> msc;
typedef queue<str> qs;
typedef vector<set<int>> vsi;
typedef priority_queue<ll> pqll;
typedef vector<vsll> vvsll;
typedef pair<ld, ld> pld;
typedef vector<vvll> vvvll;
typedef set<ld> sld;
typedef vector<vpld> vvpld;
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update>
ordered_set;
typedef tree<ll, null_type, less_equal<ll>, rb_tree_tag, tree_order_statistics_node_update>
ordered_multiset;
// \\\\\\\\\\**TYPEDEFS - END**\\\\\\\\\\
// */
// /*
// //////////**CONSTANTS - START**//////////
const ld pi = acosl(-1);
const ll mod1 = 1e9 + 7;
const ll mod2 = 998244353;
const ll MAXLL = 9223372036854775807;
//const ll MAXINT = 2147483647;
const ld eps = 1e-6;
// \\\\\\\\\\**CONSTANTS - END**\\\\\\\\\\
// */
// /*
// //////////**TEMPLATES - START**//////////
template<typename T>
istream &operator>>(istream &in, vector<T> &a) {
for (T &i: a) in >> i;
return in;
}
template<typename T1, typename T2>
istream &operator>>(istream &in, pair<T1, T2> &a) {
in >> a.fi >> a.se;
return in;
}
template<typename T1, typename T2>
ostream &operator<<(ostream &out, pair<T1, T2> a) {
out << a.fi << " " << a.se;
return out;
}
template<typename T1, typename T2>
istream &operator>>(istream &in, vector<pair<T1, T2>>
&a) {
for (
pair<T1, T2> &i
: a)
in >> i.fi >> i.
se;
return
in;
}
template<typename T>
ostream &operator<<(ostream &out, const vector<T> &a) {
for (auto i: a) {
out << i << " ";
}
return out;
}
template<typename T1, typename T2>
ostream &operator<<(ostream &out, vector<pair<T1, T2>>
&a) {
for (
pair<T1, T2> i
: a)
out << i.fi << " " << i.se <<
endl;
return
out;
}
template<typename T1>
ostream &operator<<(ostream &out, vector<vector<T1>> &a) {
for (vector<T1> i: a) {
for (T1 j: i) out << j << " ";
out << endl;
}
return out;
}
template<typename T1, typename T2>
inline T1 min(T1 a, T2 b) {
b = (T1) b;
return a > b ? b : a;
}
template<typename T1, typename T2>
inline T1 max(T1 a, T2 b) {
b = (T1) b;
return a > b ? a : b;
}
template<typename T1, typename T2>
inline void amin(T1 &a, T2 b) {
a = min(a, b);
}
template<typename T1, typename T2>
inline void amax(T1 &a, T2 b) {
a = max(a, b);
}
// \\\\\\\\\\**TEMPLATES - END**\\\\\\\\\\
// */
// This bear is a good alternative to duck!!!
/*
???? ??????
???????????????????
???????????????? ???
??? ??????????? ???
??? ???????????? ??
??????????????????
??????????????? ?
?????????????????
??????? ??? ??
???? ??????????
???? ?? ???
???????????? ?????
????????????????????
???????? ?? ???????
??????? ?????
*/
ld getTime() {
return (ld) clock() / (ld) CLOCKS_PER_SEC;
}
mt19937_64 rn(chrono::steady_clock::now().time_since_epoch().count());
//mt19937_64 rn(4);
ll rnd(ll l, ll r) {
ll a = rn() % (r - l + 1) + l;
return a;
}
void solve();
ll T = 1;
signed main(int argc, char **argv) {
// setlocale(LC_ALL, "RUS");
fastIO()
cout.precision(12);
cout << fixed;
if (local && argc == 1) {
freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
}
// cin >> T;
while (T--) {
solve();
}
if (local && argc == 1) {
cout << endl << fixed << "time = " << getTime();
}
return 0;
}
/*
___ __ __ ______ __ _____ __ __ __ __
/ | _____/ /___ ______ _/ / / ____/___ ____/ /__ / ___// /_____ ______/ /______ / / / /__ ________
/ /| |/ ___/ __/ / / / __ `/ / / / / __ \/ __ / _ \ \__ \/ __/ __ `/ ___/ __/ ___/ / /_/ / _ \/ ___/ _ \
/ ___ / /__/ /_/ /_/ / /_/ / / / /___/ /_/ / /_/ / __/ ___/ / /_/ /_/ / / / /_(__ ) / __ / __/ / / __/
/_/ |_\___/\__/\__,_/\__,_/_/ \____/\____/\__,_/\___/ /____/\__/\__,_/_/ \__/____/ /_/ /_/\___/_/ \___/
*/
ll fpow(ll b, ll m, ll mod = MAXLL) {
ll ans = 1 % mod;
ll x = b;
while (m != 0) {
if (m % 2 == 1) ans *= x;
ans %= mod;
x *= x;
x %= mod;
m /= 2;
}
return ans;
}
ll mtf(ll a, ll b, ll mod) {
return ((a % mod) * fpow((b % mod), (mod - 2), mod)) % mod;
}
const ll N = 3005;
ll dp[N][N], f[N], rf[N];
void prec() {
f[0] = rf[0] = 1;
for1(i, N) f[i] = (i * f[i - 1]) % mod1, rf[i] = mtf(1, f[i], mod1);
}
ll cnk(ll n, ll k) {
ret f[n] * rf[k] % mod1 * rf[n - k] % mod1;
}
ll g(ll n, ll m) {
if (dp[n][m] != -1) ret dp[n][m];
dp[n][m] = 1;
if (n > 1 && m > 0)
dp[n][m] = (dp[n][m] + g(n - 2, m - 1) *
cnk(n, 2) % mod1 * cnk(m, 1)) % mod1;
if (n > 0 && m > 1)
dp[n][m] = (dp[n][m] + g(n - 1, m - 2) *
cnk(n, 1) % mod1 * cnk(m, 2)) % mod1;
dp[n][m] = (dp[n][m] + 4 * g(n - 1, m - 1) * (n * m)) % mod1;
ret dp[n][m];
}
void solve() {
prec();
memset(dp, -1, sizeof dp);
ll n, m;
cin >> n >> m;
cout << (g(n, m) - 1 + mod1) % mod1;
}
