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#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())
template<class A, class B> auto& operator<<(ostream &o, pair<A, B> p) {
    return o << '(' << p.first << ", " << p.second << ')';
}
template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) {
    o << '{'; int i = 0; for(auto e : x) o << (", ")+2*!i++ << e; return o << '}';
}
ostream& operator<<(ostream &o, string &s) {
    return o << s.data();   
}
#ifdef DEBUG
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "), ...); }(x), cerr << '\n'
#else
#define debug(...) {}
#endif

const int MAXN = 3003;

LL dp[MAXN][MAXN][2];

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int n, k;
    constexpr LL mod = (LL) (1e9 + 7);
    cin >> n >> k;
    dp[0][0][0] = 1;
    FOR(i, 1, n) {
        FOR(j, 1, i) {
            dp[i][j][0] = (dp[i - 1][j][0] + dp[i - 1][j][1]) * (LL) (j);
            dp[i][j][0] %= mod;
            dp[i][j][1] = dp[i - 1][j - 1][0] * (LL) (k - j + 1) 
                        + dp[i - 1][j][1] * (LL) (k - j);
            dp[i][j][1] %= mod;
        }
    }

    LL ans = 0;
    FOR(i, 1, n) {
        ans += dp[n][i][0];
        ans %= mod;
    }
    cout << ans << '\n';

    return 0;
}