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#include <bits/stdc++.h>

using namespace std;

#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define ll long long
ll mod=1000000007;
int inf=1000000007;
ll infl=1000000000000000007;

const int N=3007;

ll DP[N][N][2];


int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    ll n,m;
    cin>>n>>m;
    DP[1][1][1]=m;
    for(ll i=1;i<n;i++)
    {
        for(ll j=1;j<=min(n,m);j++)
        {
            DP[i+1][j+1][1]=(DP[i+1][j+1][1]+DP[i][j][0]*(m-j))%mod;
            DP[i+1][j][0]=(DP[i+1][j][0]+DP[i][j][0]*j)%mod;

            DP[i+1][j][0]=(DP[i+1][j][0]+DP[i][j][1]*j)%mod;
            DP[i+1][j][1]=(DP[i+1][j][1]+DP[i][j][1]*(m-j))%mod;
        }
    }
    ll ans=0;
    for(ll j=1;j<=min(n,m);j++)
    {
        ans=(ans+(DP[n-1][j][0]+DP[n-1][j][1])*j)%mod;
    }
    cout<<ans;

    return 0;
}