#include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <ios>
#include <iomanip>
#include <queue>
#include <numeric>
#include <map>
#include <set>
#include <sstream>
#include <bitset>
#include <climits>
#include <stack>
#include <regex>
#include <functional>
#include <random>
#ifdef _WIN64
#  include <atcoder/all>
#endif
#ifdef _MSC_VER
#  include <intrin.h>
#  define __builtin_popcount __popcnt
#  define __builtin_popcountl __popcnt64
#endif

using namespace std;

#define ll long long
#define rep(i, init, n) for(ll i = init; i < (ll)n; i++)
#define rrep(i, init, n) for(ll i = init; i >= (ll)n; i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) (ll)(x.size())
#define Out(x) cout << x << endl
#define Yes cout << "Yes" << endl
#define No cout << "No" << endl
#define Ans cout << ans << endl
#define PI 3.14159265358979
#define MOD 1000000007

const int inf32 = INT_MAX / 2;
const ll inf64 = 1LL << 60;
template<class T>bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }

// -------------------------------------------------------------------------------------------------

struct mint
{
	ll x;

	mint(ll val = 0) { x = (val % MOD + MOD) % MOD; }

	mint operator-() const { return mint(-x); }
	mint& operator+=(const mint& other) { x += other.x; if (x >= MOD) x -= MOD; return *this; }
	mint& operator-=(const mint& other) { x -= other.x; if (x < 0) x += MOD; return *this; }
	mint& operator*=(const mint& other) { (x *= other.x) %= MOD; return *this; }
	mint& operator/=(const mint& other) { *this *= other.pow(MOD - 2); return *this; }
	mint operator+(const mint& other) const { return mint(*this) += other; }
	mint operator-(const mint& other) const { return mint(*this) -= other; }
	mint operator*(const mint& other) const { return mint(*this) *= other; }
	mint operator/(const mint& other) const { return mint(*this) /= other; }

	mint pow(ll i) const
	{
		mint ret = 1;
		for (mint tmp = x; i; tmp *= tmp, i >>= 1) if (i & 1) ret *= tmp;
		return ret;
	}

	friend ostream& operator<<(ostream& os, const mint& m) { os << m.x; return os; }
};
struct Combination
{
	vector<ll> f, finv;
	bool precalc = false;

	Combination(ll n, bool calc_inv = false)
	{
		f.resize(n + 1);
		if (calc_inv) finv.resize(n + 1), precalc = true;

		f[0] = 1;
		rep(i, 1, n + 1) f[i] = f[i - 1] * i % MOD;
		if (calc_inv) rep(i, 0, n + 1) finv[i] = mpow(f[i], MOD - 2);
	}

	ll mpow(ll x, ll y)
	{
		if (y == 0) return 1;

		x %= MOD;
		if (x == 0) return 0;

		if (y % 2 == 0) return mpow(x * x % MOD, y / 2) % MOD;
		else return x * mpow(x, y - 1) % MOD;
	}

	ll P(ll x, ll y) { return precalc ? f[x] * finv[x - y] % MOD : f[x] * mpow(f[x - y], MOD - 2) % MOD; }

	ll C(ll x, ll y)
	{
		ll a = f[x];
		ll b = precalc ? finv[y] * finv[x - y] % MOD : mpow(f[y] * f[x - y] % MOD, MOD - 2);

		return a * b % MOD;
	}

	ll H(ll x, ll y) { return C(x + y - 1, y); }
};
ll mpow(ll x, ll y)
{
	if (y == 0) return 1;

	x %= MOD;
	if (x == 0) return 0;

	if (y % 2 == 0) return mpow(x * x % MOD, y / 2) % MOD;
	else return x * mpow(x, y - 1) % MOD;
}

int main()
{
	ll n, m; cin >> n >> m;

	Combination comb(100000, true);
	mint ans = mpow(m, n);

	rep(i, 1, m)
	{
		mint tmp = (mint)comb.C(m, i) * mpow(i, n);
		ans += tmp * ((m - i) % 2 != 0 ? -1 : 1);
	}

	Ans;

	return 0;
}