#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 3018;
const int MOD = 1e9 + 7;
//#define debug(...) fprintf(stderr, __VA_ARGS__)
#define debug(...)
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define fillchar(a, s) memset((a), (s), sizeof(a))
void addeq (int &x, int y) {
x += y;
if (x >= MOD) {
x -= MOD;
}
}
int add (int x, int y) {
addeq(x, y);
return x;
}
int mult (int x, int y) {
return ll(x) * y % MOD;
}
int mult (int x, int y, int z) {
return mult(mult(x, y), z);
}
int mult (int x, int y, int z, int w) {
return mult(mult(x, y), mult(z, w));
}
int cho2[MAXN];
void precomp() {
for (int i = 2; i < MAXN; i++) {
cho2[i] = i * (i - 1) / 2;
}
}
int N, M;
int dp[MAXN][MAXN];
int psum1[MAXN][MAXN], psum2[MAXN][MAXN], psum3[MAXN][MAXN];
void compute_psum (int j) {
int p = 0;
for (int i = 0; i <= N; i++) {
addeq(p, mult(4, j + 1, dp[i][j]));
psum1[i][j] = p;
}
p = 0;
for (int i = 0; i <= N; i++) {
addeq(p, mult(cho2[j + 2], dp[i][j]));
psum2[i][j] = p;
}
p = 0;
for (int i = 0; i <= N; i++) {
addeq(p, mult(j + 1, i + 1, dp[i][j]));
psum3[i][j] = p;
}
}
int main() {
precomp();
scanf("%d %d", &N, &M);
for (int i = 0; i < MAXN; i++) {
for (int j = 0; j < MAXN; j++) {
dp[i][j] = 1;
}
}
compute_psum(0);
for (int j = 1; j <= M; j++) {
for (int i = 1; i <= N; i++) {
addeq(dp[i][j], psum1[i - 1][j - 1]);
if (j > 1) {
addeq(dp[i][j], psum2[i - 1][j - 2]);
}
if (i > 1) {
addeq(dp[i][j], psum3[i - 2][j - 1]);
}
}
compute_psum(j);
}
printf("%d\n", add(dp[N][M], MOD - 1));
}
