#include<iostream>
using namespace std;
const long mod=1e9+7;
long power(long a,long b){return b?power(a*a%mod,b/2)*(b%2?a:1)%mod:1;}
long fac[1<<17],inv[1<<17];
int N,M;
main()
{
	cin>>N>>M;
	fac[0]=1;
	for(int i=1;i<=N;i++)fac[i]=fac[i-1]*i%mod;
	inv[N]=power(fac[N],mod-2);
	for(int i=N;i--;)inv[i]=inv[i+1]*(i+1)%mod;
	long ans=0;
	for(int i=M;i;i--)
	{
		long now=fac[M]*inv[i]%mod*inv[M-i]%mod*power(i,N)%mod;
		if((M-i)%2==0)ans+=now;
		else ans-=now;
	}
	cout<<(ans%mod+mod)%mod<<endl;
}