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#include <iostream>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
#include <string>
#include <bitset>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <algorithm>
#include <sstream>
#include <stack>
#include <iomanip>
#include <assert.h>
using namespace std;
#define pb push_back
#define mp make_pair
typedef pair<int,int> pii;
typedef long long ll;
typedef double ld;
typedef vector<int> vi;
#define fi first
#define se second
#define fe first
#define FO(x) {freopen(#x".in","r",stdin);freopen(#x".out","w",stdout);}
#define Edg int M=0,fst[SZ],vb[SZ],nxt[SZ];void ad_de(int a,int b){++M;nxt[M]=fst[a];fst[a]=M;vb[M]=b;}void adde(int a,int b){ad_de(a,b);ad_de(b,a);}
#define Edgc int M=0,fst[SZ],vb[SZ],nxt[SZ],vc[SZ];void ad_de(int a,int b,int c){++M;nxt[M]=fst[a];fst[a]=M;vb[M]=b;vc[M]=c;}void adde(int a,int b,int c){ad_de(a,b,c);ad_de(b,a,c);}
#define es(x,e) (int e=fst[x];e;e=nxt[e])
#define esb(x,e,b) (int e=fst[x],b=vb[e];e;e=nxt[e],b=vb[e])
const int MOD=1e9+7;
int n,m; ll f[3005][2][3005];
int main()
{
	scanf("%d%d",&n,&m);
	f[0][1][0]=1;
	for(int i=1;i<=n;++i) {
		for(int o=0;o<2;++o) {
			ll F;
			for(int j=0;j<i;++j) if(F=f[i-1][o][j]) {
				(f[i][1][j]+=F*j)%=MOD;
				(f[i][0][j+o]+=F*(m-j))%=MOD;
			}
		}
	}
	ll ans=0;
	for(int i=0;i<=n;++i) (ans+=f[n][1][i])%=MOD;
	ans=(ans%MOD+MOD)%MOD;
	cout<<ans<<"\n";
}