#include<bits/stdc++.h>
using namespace std ;
typedef long long ll ;
typedef unsigned long long ull ;
// mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const int MOD = 1e9 + 7 ;
const int MAXN = 3007 ;
int n , m ;
ll fac[ MAXN ] , inv[ MAXN ] ;
ll fastpow ( ll x , ll pw ) {
ll ret = 1 ;
while ( pw > 0 ) {
if ( ( pw % 2 ) == 0 ) {
x = ( x * x ) % MOD ;
pw /= 2 ;
}
else {
ret = ( ret * x ) % MOD ;
-- pw ;
}
}
return ret ;
}
ll take_single[ MAXN ][ MAXN ] ;
ll cons[ MAXN ][ MAXN ] ;
ll comb ( int up , int down ) {
if ( up < down || down < 0 ) { return 0 ; }
ll ret = fac[ up ] ;
ret = ( ret * inv[ down ] ) % MOD ;
ret = ( ret * inv[ up - down ] ) % MOD ;
return ret ;
}
void solve ( ) {
cin >> n >> m ;
fac[ 0 ] = 1 ;
for ( int i = 1 ; i < MAXN ; ++ i ) {
fac[ i ] = ( fac[ i - 1 ] * i ) % MOD ;
}
inv[ MAXN - 1 ] = fastpow ( fac[ MAXN - 1 ] , MOD - 2 ) ;
for ( int i = MAXN - 2 ; i >= 0 ; -- i ) {
inv[ i ] = ( inv[ i + 1 ] * ( i + 1 ) ) % MOD ;
}
for ( int i = 0 ; i <= n ; ++ i ) {
take_single[ i ][ 0 ] = 1 ;
}
for ( int i = 0 ; i <= m ; ++ i ) {
take_single[ 0 ][ i ] = 1 ;
}
for ( int i = 1 ; i <= n ; ++ i ) {
for ( int j = 1 ; j <= m ; ++ j ) {
take_single[ i ][ j ] = ( take_single[ i - 1 ][ j ] + 4 * j * take_single[ i - 1 ][ j - 1 ] ) % MOD ;
}
}
for ( int i = 0 ; i < MAXN ; ++ i ) {
cons[ 0 ][ i ] = 1 ;
}
for ( int cnt = 1 ; cnt < MAXN ; ++ cnt ) {
for ( int i = 2 * cnt ; i < MAXN ; ++ i ) {
ll coef = ( 1LL * i * ( i - 1 ) * inv[ 2 ] ) % MOD ;
cons[ cnt ][ i ] = ( coef * cons[ cnt - 1 ][ i - 2 ] ) % MOD ;
}
}
ll ans = 0 ;
for ( int i = 0 ; i <= n ; ++ i ) {
for ( int j = 0 ; j <= m ; ++ j ) {
int x = n - i - 2 * j , y = m - 2 * i - j ;
if ( x < 0 || y < 0 ) { continue ; }
ll aux = comb ( n , i ) ;
aux = ( aux * cons[ i ][ m ] ) % MOD ;
aux = ( aux * comb ( m - 2 * i , j ) ) % MOD ;
aux = ( aux * cons[ j ][ n - i ] ) % MOD ;
aux = ( aux * take_single[ x ][ y ] ) % MOD ;
ans = ( ans + aux ) % MOD ;
}
}
cout << ( ans - 1 + MOD ) % MOD << "\n" ;
}
int main ( ) {
ios_base :: sync_with_stdio ( false ) ;
cin.tie ( NULL ) ;
int t = 1 ; // cin >> t ;
while ( t -- ) { solve ( ) ; }
return 0 ;
}
