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#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
const ll mod=1000000007;
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=3010;

int dp[N][N][2];
int n,m;
int main() {
	scanf("%d%d",&n,&m);
	dp[0][0][0]=1;
	rep(i,0,n) rep(j,0,i+1) {
		dp[i+1][j][0]=(dp[i+1][j][0]+(ll)(dp[i][j][0]+dp[i][j][1])*j)%mod;
		dp[i+1][j+1][1]=(dp[i+1][j+1][1]+(ll)dp[i][j][0]*(m-j))%mod;
		dp[i+1][j][1]=(dp[i+1][j][1]+(ll)dp[i][j][1]*(m-j))%mod;
	}
	ll ans=0;
	rep(i,0,n+1) ans=(ans+dp[n][i][0])%mod;
	printf("%lld\n",ans);
}