#include <bits/stdc++.h>

using namespace std;
using ll = long long;
// #define int ll
using PII = pair<ll, ll>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()

template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }

template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }

template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
    out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
    for(T& x: vec) {is >> x;} return is;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
    out<<'['; for(T i: a) {out<<i<<',';} out<<']'; return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;

template<bool bigN=false>
ll combi(ll N_, ll K_, ll mo=MOD) {
  const int NUM_=5e5;
  static ll fact[NUM_+1]={},factr[NUM_+1]={},inv[NUM_+1]={};
  auto binpow = [&](ll x, ll e) -> ll {
    ll a = 1, p = x;
    while(e > 0) {
      if(e%2 == 0) {p = (p*p) % mo; e /= 2;}
      else {a = (a*p) % mo; e--;}
    }
    return a;
  };
  if (fact[0]==0) {
    if(!bigN) {
      fact[0] = factr[0] = inv[0] = 1;
      FOR(i, 1, NUM_+1) fact[i] = fact[i-1] * i % MOD;
      factr[NUM_] = binpow(fact[NUM_], mo-2);
      for(int i=NUM_-1; i>=0; --i) factr[i] = factr[i+1] * (i+1) % MOD;
    } else {
      FOR(i, 1, NUM_+1) fact[i] = fact[i-1] * i % MOD;
      REP(i, NUM_+1) inv[i] = binpow(i, MOD-2);
    }
  }
  if(K_<0 || K_>N_) return 0;
  // 前計算 O(max(N,K)) クエリ O(1)
  if(!bigN) return factr[K_]*fact[N_]%MOD*factr[N_-K_]%MOD;
  // Nが大きいけどKが小さい場合に使う 前計算 O(Klog(mod)) クエリ O(K)
  ll ret = 1;
  for(;K_>0;N_--,K_--) (ret *= N_%MOD) %= MOD, (ret *= inv[K_]) %= MOD;
  return ret;
}

ll binpow(ll x, ll e) {
  ll ret = 1, p = x;
  while(e > 0) {
    if(e&1) {(ret *= p) %= MOD; e--;}
    else {(p *= p) %= MOD; e /= 2;} 
  }
  return ret;
}

struct mint {
  ll x;
  mint(): x(0) { }
  mint(ll y) : x(y>=0 ? y%MOD : y%MOD+MOD) {}
  ll get() const { return x; }
  // e乗
  mint pow(ll e) {
    ll a = 1, p = x;
    while(e > 0) {
      if(e%2 == 0) {p = (p*p) % MOD; e /= 2;}
      else {a = (a*p) % MOD; e--;}
    }
    return mint(a);
  }
  // Comparators
  bool operator <(mint b) { return x < b.x; }
  bool operator >(mint b) { return x > b.x; }
  bool operator<=(mint b) { return x <= b.x; }
  bool operator>=(mint b) { return x >= b.x; }
  bool operator!=(mint b) { return x != b.x; }
  bool operator==(mint b) { return x == b.x; }
  // increment, decrement
  mint operator++() { x++; return *this; }
  mint operator++(signed) { mint t = *this; x++; return t; }
  mint operator--() { x--; return *this; }
  mint operator--(signed) { mint t = *this; x--; return t; }
  // Basic Operations
  mint &operator+=(mint that) {
    x += that.x;
    if(x >= MOD) x -= MOD;
    return *this;
  }
  mint &operator-=(mint that) {
    x -= that.x;
    if(x < 0) x += MOD;
    return *this;
  }
  mint &operator*=(mint that) {
    x = (ll)x * that.x % MOD;
    return *this;
  }
  mint &operator/=(mint that) {
    x = (ll)x * that.pow(MOD-2).x % MOD;
    return *this;
  }
  mint &operator%=(mint that) {
    x = (ll)x % that.x;
    return *this;
  }
  mint operator+(mint that) const { return mint(*this) += that; }
  mint operator-(mint that) const { return mint(*this) -= that; }
  mint operator*(mint that) const { return mint(*this) *= that; }
  mint operator/(mint that) const { return mint(*this) /= that; }
  mint operator%(mint that) const { return mint(*this) %= that; }
};
// Input/Output
ostream &operator<<(ostream& os, mint a) { return os << a.x; }
istream &operator>>(istream& is, mint &a) { return is >> a.x; }

signed main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll n, k;
    cin >> n >> k;

    mint ans = 0;
    REP(i, k+1) {
        if(i%2) ans -= combi(k, i) * binpow(k - i, n);
        else ans += combi(k, i) * binpow(k - i, n);
    }
    cout << ans << endl;

    return 0;
}



Measured memory_bytes: 11024