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#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define e1 first
#define e2 second
#define pb push_back
#define OUT(x) {cout << x << "\n"; exit(0); }
#define TCOUT(x) {cout << x << "\n"; return; }
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define rep(i, l, r) for(int i = (l); i < (r); ++i)
#define boost {ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); }
#define sz(x) int(x.size())
#define trav(a, x) for(auto& a : x)
#define all(x) begin(x), end(x)
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;

ll safe_mod(ll x, ll m) {
	ll t = x%m;
	return t >= 0 ? t : t + m;
}

struct mint {
	static const ll mod = 1000000007; // change to something else
	ll x;
	ll val() {
		x %= mod;
		return x;
	}
	mint() : x(0) {}
	mint(ll xx) : x(safe_mod(xx, mod)) {}
	mint operator+(mint b) { return mint((x + b.x) % mod); }
	void operator+=(mint b) {
		x = (x + b.x) % mod;
	}
	mint operator-(mint b) { return mint((x - b.x + mod) % mod); }
	mint operator*(mint b) { return mint((x * b.x) % mod); }
	mint operator^(ll e) {
		ll ans = 1, b = x;
		for (; e; b = b * b % mod, e /= 2)
		if (e & 1) ans = ans * b % mod;
		return ans;
	}
};

mt19937_64 rng(time(0));
int random(int l, int r) {
	return uniform_int_distribution<int>(l, r)(rng);
}
#ifdef DEBUG
template<class T> int size(T &&x) {
	return int(x.size());
}
template<class A, class B> ostream& operator<<(ostream &out, const pair<A, B> &p) {
	return out << '(' << p.first << ", " << p.second << ')';
}
template<class T> auto operator<<(ostream &out, T &&x) -> decltype(x.begin(), out) {
	out << '{';
	for(auto it = x.begin(); it != x.end(); ++it)
		out << *it << (it == prev(x.end()) ? "" : ", ");
	return out << '}';
}
void dump() {}
template<class T, class... Args> void dump(T &&x, Args... args) {
	cerr << x << ";  ";
	dump(args...);
}
#endif
#ifdef DEBUG
  struct Nl{~Nl(){cerr << '\n';}};
# define debug(x...) cerr << (strcmp(#x, "") ? #x ":  " : ""), dump(x), Nl(), cerr << ""
#else
# define debug(...) 0 && cerr
#endif

//Did you REAALLY consider sample tests?

int cuttable(vi config) {
	int n = sz(config);
	vi dp(n + 1, 0);
	config.pb(-1);
	reverse(all(config));
	
	dp[0] = 1;
	FOR(i, 1, n) {
		if (dp[i-1]) {
			FOR(j, i+1, n) {
				if (config[i] == config[j]) dp[j] = 1;
			}
		}
	}
	
	return dp[n];
}

mint brut(int n, int m) {
	// there are m^n configurations
	
	mint em = m;
	mint all = em^n;
	int vall = all.val();
	
	mint res = 0;
	for (int i=0; i<vall; ++i) {
		vi config(n, 0);
		int mask = i;
		rep(j, 0, n) {
			config[j] = (mask % m);
			mask /= m;
		}
		
		int bit = cuttable(config);
		res += bit;
	}
	
	return res;
}

const int maxn = 3010;
mint dp[maxn][maxn][2];
mint wzo(int n, int M) {
	rep(i, 0, maxn) rep(j, 0, maxn) rep(bit, 0, 2) dp[i][j][bit] = 0;
	dp[1][1][0] = M;
	
	for (int N = 1; N < n; ++N) {
		for (int K = 1; K <= min(M, N); ++K) {
			dp[N+1][K][0] += dp[N][K][0] * (M - K);
			dp[N+1][K][1] += dp[N][K][0] * K;
			dp[N+1][K+1][0] += dp[N][K][1] * (M - K);
			dp[N+1][K][1] += dp[N][K][1] * K;
		}
	}
	
	mint res = 0;
	for (int i = 1; i <= n; ++i) res += dp[n][i][1];
	return res;
}

bool TEST = 0;

int main() {
	int n, k;
	cin >> n >> k;	
	if (!TEST) {
		cout << wzo(n, k).val() << "\n";
	}
	else {
		for (int i=1; i<=n; ++i) {
			for (int j=1; j<=k; ++j) {
				printf("%6d ", brut(i, j).val());
			}
			cout << "\n";
		}
		
		for (int i=1; i<=n; ++i) {
			for (int j=1; j<=k; ++j) {
				printf("%6d ", wzo(i, j).val());
			}
			cout << "\n";
		}
	}
}