#ifdef LOCAL111
#else
	#define NDEBUG
#endif
#include <bits/stdc++.h>
const int INF = 1e8;
using namespace std;

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define RBP(i,a) for(auto& i : a)
#ifdef LOCAL111
	#define DEBUG(x) cout<<#x<<": "<<(x)<<endl
#else
	#define DEBUG(x) true
#endif
#define F first
#define S second
#define SNP string::npos
#define WRC(hoge) cout << "Case #" << (hoge)+1 << ": "
#define rangej(a,b,c) ((a) <= (c) and (c) < (b))
#define rrangej(b,c) rangej(0,b,c)
template<typename T> void pite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}

typedef pair<int,int> P;
typedef long long int LL;
typedef unsigned long long ULL;
typedef pair<LL,LL> LP;

void ios_init(){
	//cout.setf(ios::fixed);
	//cout.precision(12);
#ifdef LOCAL111
	return;
#endif
	ios::sync_with_stdio(false); cin.tie(0);	
}

const LL mod = 1e9+7;

//res.first*a+res.second*b == 1 となるresを返す (a,bは互いに素)
pair<long long, long long> extgcd(long long a,long long b)
{
	if(b==1){
		return pair<long long, long long>(0,1);
	}
	pair<long long, long long> t=extgcd(b,a%b);
	return pair<long long, long long>(t.second,t.first-a/b*t.second);
}

//modの逆元を返す
long long inverse(long long mod,long long a)
{
	return (extgcd(mod,a).second+mod)%mod;
}


long long modpow(long long a, long long b){
	LL res = 1;
	while(b != 0){
		if(b&1) res = res*a%mod;
		a = a*a%mod;
		b >>= 1;
	}
	return res;
}

int main()
{
	ios_init();
	LL n, m;
	cin >> n >> m;
	LL comb = 1;
	int sgn = 1;
	LL ans = 0;
	REP(j,m+1){
		ans += sgn*comb*modpow(m-j,n)%mod;
		sgn *= -1;
		comb = comb*inverse(mod,j+1)%mod*(m-j)%mod;
		ans %= mod;
		ans += mod;
		ans %= mod;
	}
	cout << ans << endl;
	return 0;
}