#include <algorithm>
#include <cmath>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <string>
#include <vector>

using namespace std;
using ll = long long;
#define rep(i, j, n) for (ll i = j; i < (n); ++i)
#define rrep(i, j, n) for (ll i = (n)-1; j <= i; --i)

template <typename T>
std::ostream &operator<<(std::ostream &os, std::vector<T> &a) {
  os << "{";
  for (size_t i = 0; i < a.size(); ++i) os << (i > 0 ? "," : "") << a[i];
  return os << "}";
}

[[maybe_unused]] constexpr ll MOD = 1e9 + 7;
[[maybe_unused]] constexpr int INF = 0x3f3f3f3f;
[[maybe_unused]] constexpr ll INFL = 0x3f3f3f3f3f3f3f3fLL;
class combination {
public:
  explicit combination(int n, uint64_t m)
    : mod(m), fact(n + 1), inv(n + 1), finv(n + 1) {
    fact[0] = finv[0] = inv[1] = 1;
    for (int i = 2; i < n + 1; ++i)
      inv[i] = mod - inv[mod % i] * (mod / i) % mod;
    for (int i = 1; i < n + 1; ++i) {
      fact[i] = fact[i - 1] * i % mod;
      finv[i] = finv[i - 1] * inv[i] % mod;
    }
  }
  uint64_t operator()(int n, int k) {
    if (n < k || n < 0 || k < 0) return 0;
    return fact[n] * finv[n - k] % mod * finv[k] % mod;
  }
  uint64_t modpow(uint64_t x, uint64_t e) {
    uint64_t res = 1;
    while (e > 0) {
      if (e & 1) res = res * x % mod;
      x = x * x % mod;
      e >>= 1;
    }
    return res;
  }

private:
  uint64_t mod;
  vector<uint64_t> fact, inv, finv;
};

int main() {
  cin.tie(0)->sync_with_stdio(0);
  ll n, m;
  cin >> n >> m;
  combination c(m, MOD);
  ll ans = 0;
  rep(i, 0, m + 1) {
    if (i & 1)
      ans += MOD - c(m, i) * c.modpow(m - i, n) % MOD;
    else
      ans += c(m, i) * c.modpow(m - i, n) % MOD;
    if (ans >= MOD) ans -= MOD;
  }
  cout << ans << '\n';

  return 0;
}