#include <bits/stdc++.h>
#define fi first
#define se second
#define FOR(i, a, b) for (int i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for (int i = a, _b = b; i >= _b; --i)
#define FORLL(i, a, b) for (ll i = a, _b = b; i <= _b; ++i)
#define FORDLL(i, a, b) for (ll i = a, _b = b; i >= _b; --i)
#define all(x) x.begin(), x.end()
#define uni(x) sort(all(x)), x.erase(unique(all(x)), x.end())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define dbg(...) debug(#__VA_ARGS__, __VA_ARGS__)
template<typename T>
void __prine_one(const char *&s, const T &x)
{
while (*s == ' ') ++s;
const char *p = s;
int bal = 0;
while (*s)
{
if (*s == '(') ++bal;
else if (*s == ')') --bal;
else if (*s == ',' && bal == 0) break;
++s;
}
cerr.write(p, s - p) << " = " << x;
if (*s == ',')
{
cerr << " , ";
++s;
}
}
template<typename... Args>
void debug(const char *s, Args... args)
{
cerr << "[ ";
int dummy[] = {0, (__prine_one(s, args), 0)...};
(void)dummy;
cerr << " ]\n\n";
}
template<class X>
bool maximize(X &a, const X &b)
{
if (a < b)
{
a = b;
return true;
}
return false;
}
template<class X>
bool minimize(X &a, const X &b)
{
if (a > b)
{
a = b;
return true;
}
return false;
}
// --------------------------------------------------------------------------------------------
const int maxn = 3005, MOD = 1e9 + 7;
int n, m;
ll fact[maxn], inv[maxn], pow4[maxn], dp[maxn][maxn], lay2[maxn][maxn];
// --------------------------------------------------------------------------------------------
ll add(ll a, ll b)
{
a += b;
if (a >= MOD) a -= MOD;
if (a < 0) a += MOD;
return a;
}
ll mul(ll a, ll b)
{
a *= b;
a %= MOD;
if (a < 0) a += MOD;
return a;
}
ll binpow(ll a, ll b)
{
ll res = 1;
for (; b; b >>= 1, a = mul(a, a))
if (b & 1) res = mul(res, a);
return res;
}
ll C(int n, int k)
{
if (k > n) return 0ll;
return mul( fact[n] , mul( inv[n - k] , inv[k] ) );
}
// ll F(ll n, ll m, ll k)
// {
// return mul( A(n, k) , mul( C(m, k) , pow4[k] ) );
// }
void solve()
{
cin >> n >> m;
pow4[0] = fact[0] = 1;
FOR(i, 1, 3000)
{
pow4[i] = mul( pow4[i - 1] , 4 );
fact[i] = mul( fact[i - 1] , i );
}
inv[3000] = binpow(fact[3000], MOD - 2);
FORD(i, 2999, 0)
inv[i] = mul( inv[i + 1] , i + 1 );
FOR(i, 1, 3000)
{
dp[1][i] = 1 + mul( 4 , i );
dp[i][1] = 1 + mul( 4 , i );
dp[0][i] = dp[i][0] = 1;
}
dp[0][0] = 1;
FOR(i, 2, n)
FOR(j, 2, m)
{
dp[i][j] = mul( 4 , mul( i , dp[i - 1][j - 1] ) );
dp[i][j] = add(dp[i][j], dp[i][j - 1]);
}
// FOR(i, 1, n)
// {
// FOR(j, 1, m)
// cout << dp[i][j] << ' ';
// cout << '\n';
// }
FOR(i, 0, 3000)
{
lay2[i][0] = 1;
lay2[i][1] = max(1ll, C(i, 2));
FOR(j, 2, i / 2)
lay2[i][j] = mul(lay2[i][1] , lay2[i - 2][j - 1]);
}
ll res = 0;
FOR(X, 0, n)
{
FOR(Y, 0, m)
{
ll cur = 1;
int row = n, col = m;
row -= X;
col -= 2 * X;
if (col < 0) break;
cur = mul( cur , C(n, X) );
cur = mul( cur , lay2[m][X]);
row -= 2 * Y; col -= Y;
if (row < 0 || col < 0) break;
cur = mul( cur , C(col + Y, Y) );
cur = mul( cur , lay2[row + 2 * Y][Y] );
cur = mul( cur , dp[row][col] );
res = add( res , cur );
}
}
cout << add(res, -1);
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define TASK "TEST"
if (fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
solve();
return 0;
}
