#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define vl vector<ll>
#define vi vector<int>
#define pb push_back
#define sz(v) (ll)(v.size())
#define f first
#define s second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
const ll sz = 305, mod = 1000000007;
ll dp[sz][sz][sz];
ll f(ll i, ll j, ll k)
{
if(i < 0 || j < 0 || k < 0)
return 0;
if(i == 0)
return 1;
ll &res = dp[i][j][k];
if(res != -1)
return res % mod;
res = f(i-1, j, k);
res %= mod;
if(k >= 1)
{
res += (k * f(i-1, j, k-1));
res %= mod;
}
if(j >= 1)
{
res += (3 * j * f(i-1, j-1, k));
res %= mod;
res += (j * f(i-1, j-1, k+1));
res %= mod;
}
if(j >= 2)
{
res += (((j * (j - 1)) / 2) * (f(i-1, j-2, k)));
res %= mod;
}
return res;
}
void solve()
{
ll h, w;
cin >> h >> w;
for(ll i = 0; i <= h + 1; i++)
{
for(ll j = 0; j <= w + 1; j++)
{
for(ll k = 0; k <= w + 1; k++)
dp[i][j][k] = -1;
}
}
ll ans = f(h, w, 0);
ans--;
if(ans < 0)
ans += mod;
cout << ans << "\n";
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
ll tests = 1;
//cin >> tests;
while(tests--)
{
solve();
}
}
