#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define OVERLOAD_REP(_1, _2, _3, name, ...) name
#define REP1(i, n) for (auto i = std::decay_t<decltype(n)>{}; (i) != (n); ++(i))
#define REP2(i, l, r) for (auto i = (l); (i) != (r); ++(i))
#define rep(...) OVERLOAD_REP(__VA_ARGS__, REP2, REP1)(__VA_ARGS__)
#define REP(i, l, r) rep(i, l, r+1)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
using ll = long long;
using ld = long double;
using P = pair<ll,ll>;
struct Edge {
  int to; ll w;
};
using Graph = vector<vector<int> >;
//using Graph = vector<vector<Edge> >;
const ll INF = 2e18;
//const int INF = 2e9;
template<class T> using vc = vector<T>;
template<class T> using vv = vector<vector<T> >;
template<class T> using vvv = vector<vector<vector<T> > >;
template<class T> using pq = priority_queue<T>;
template<class T> using pq_g = priority_queue<T, vc<T>, greater<T> >;
template<class T> istream& operator>>(istream& i, vc<T>& v) { rep(j, 0, v.size()) i>>v[j]; return i; }
template<class T> ostream& operator<<(ostream& o, vc<T>& v) { rep(j, 0, v.size()) o<<v[j]<<" "; return o; }
template<class T> bool chmin(T& a, T b) {
  if(a > b) {
      a = b;
      return true;
  }
  return false;
}
template<class T> bool chmax(T& a, T b) {
  if(a < b) {
      a = b;
      return true;
  }
  return false;
}
constexpr double EPS = 1e-9;

inline bool eq(double a, double b) { return fabs(a - b) < EPS; }
inline bool lt(double a, double b) { return a < b - EPS; }
inline bool gt(double a, double b) { return a > b + EPS; }
inline int sgn(double x) {
    if (x > EPS) return 1;
    if (x < -EPS) return -1;
    return 0;
}

ll mod = 1000000007;
int fact_nums = 200000;
vc<ll> fact;
void fact_() {
    fact.resize(fact_nums);
    fact[0] = 1;
    REP(i, 1, fact_nums) fact[i] = fact[i-1] * i % mod;
}
ll powmod(ll x, ll n) {
    ll ans = 1;
    ll base = x % mod;
    while(n) {
        if(n%2) {
            ans = (ans * base) % mod;
        }
        base = base*base%mod;
        n >>= 1;
    }
    return ans;
}
ll nCr(ll n, ll r) {
    return fact[n] * powmod(fact[r] * fact[n-r] % mod, mod-2) % mod;
}
int main() {
  // 高速化
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  // 小数点の出力桁数を指定
  cout << fixed << setprecision(10);
  // メイン
  ll N, M;
  cin >> N >> M;
  //N %= mod;
  fact_();
  ll ans = 0;
  REP(i, 0, M) {
      if((M-i)%2) ans -= nCr(M, i) * powmod(i, N) % mod;
      else ans += nCr(M, i) * powmod(i, N) % mod;
      ans = (ans+mod)%mod;
  }
  cout << ans << endl;

  return 0;
}