#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

template<int MOD>
class ModInt{
public:
    ModInt():value(0){}
    ModInt(int val):value(val<0?MOD+val%MOD:val%MOD){ }
    
    ModInt& operator+=(ModInt that){
        value = value+that.value;
        if(value>=MOD)value-=MOD;
        return *this;
    }
    ModInt& operator-=(ModInt that){
        value -= that.value;
        if(value<0)value+=MOD;
        return *this;
    }
    ModInt& operator*=(ModInt that){
        value = (int)((long long)value * that.value % MOD);
        return *this;
    }
    ModInt &operator/=(ModInt that){
        return *this *= that.inverse();
    }
    ModInt operator+(ModInt that) const{
        return ModInt(*this)+=that;
    }
    ModInt operator-(ModInt that) const{
        return ModInt(*this)-=that;
    }
    ModInt operator*(ModInt that) const{
        return ModInt(*this)*=that;
    }
    ModInt operator/(ModInt that) const {
        return ModInt(*this) /= that;
    }
    ModInt operator^(long long k) const{
        ModInt n = *this, res = 1;
        while(k){
            if(k & 1)res *= n;
            n *= n;
            k >>= 1;
        }
        return res;
    }
    ModInt inverse() const {
        long long a = value, b = MOD, u = 1, v = 0;
        while(b) {
            long long t = a / b;
            a -= t * b;
            swap(a, b);
            u -= t * v;
            swap(u, v);
        }
        return ModInt(u);
    }
    int toi() const{ return value; }

private:
    int value;
};
typedef ModInt<1000000007> mint;
ostream& operator<<(ostream& os, const mint& x){
    os << x.toi();
    return os;
}

// n以下の階乗を返す
template <class Val>
vector<Val> factorials(int n){
    vector<Val> res(n + 1);
    res[0] = res[1] = 1;
    for(int i = 2; i <= n; ++i)
        res[i] = res[i - 1] * i;
    return res;
}

mint nCr(int n, int r, const vector<mint> &fact){
    return fact[n] / (fact[r] * fact[n - r]);
}

/*
|A|>=|B|を満たす空でない集合A,Bについて
|A|=n, |B|=kとおく。
このとき、f:A->B であるようなすべての全射関数を数える。
O(klog(n))
検証済み
*/
mint countSurjectiveFunctions(long long n, int k, const vector<mint> &fact){
    mint res = 0;
    for(int i = 1; i <= k; ++i){
        mint d = nCr(k, i, fact);
        d *= (mint(i)^n);
        if((k - i) % 2)d *= -1;
        res += d;
    }
    return res;
}

ll N;
int M;

int main(){
    while(cin >> N >> M){
        if(M > N){
            puts("0");
            continue;
        }

        auto f = factorials<mint>(M);
        mint ans = countSurjectiveFunctions(N, M, f);
        cout << ans << endl;
    }
}