#include <stdio.h>

typedef long long LL;

#define range(i,a,b) for(int i=(a); i < (b); i++)
#define rep(i,n) range(i,0,n)

#define U 200000
#define P 1000000007

LL mypow(LL b,LL e){
	LL ret = 1;
	for (;e>0;e>>=1){
		if(e&1) ret = ret * b % P;
		b = b * b % P;
	}
	return ret;
}
LL F[U+1],FI[U+1];
int main(){
	LL N,M,ans=0;
	scanf("%lld %lld",&N,&M);
	F[0] = 1;
	rep(i,M) F[i+1] = (i+1)*F[i]%P;
	FI[M] = mypow(F[M],P-2);
	rep(i,M) FI[M-1-i] = (M-i)*FI[M-i]%P;
	rep(k,M) ans = (ans+(k%2?-1:1)*(F[M]*FI[k]%P*FI[M-k]%P)*mypow(M-k,N)+P)%P;
	printf("%lld\n",ans);
	return 0;
}