#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T> using treap = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define int long long
#define REP(i, n) for (long long i = 0, max_i = (n); i < max_i; i++)
#define REPI(i, a, b) for (long long i = (a), max_i = (b); i < max_i; i++)
#define ALL(obj) begin(obj), end(obj)
#define RALL(obj) rbegin(obj), rend(obj)
#define fi first
#define se second
using ii = pair<int, int>;
vector<ii> dirs = {
  {1, 0}, {0, 1}, {-1, 0}, {0, -1},  // 4方向
  {1, 1}, {-1, 1}, {-1, -1}, {1, -1},  // 斜め
  {0, 0},  // 自身
};
template <class T> inline bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } return false; }
template <class T> inline bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; } return false; }
template <class T, class S> vector<T> make_vec(size_t n, S x) { return vector<T>(n, x); }
template <class T, class... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec<T>(ts...))>(n, make_vec<T>(ts...)); }

// debug
template <class T> ostream& operator<<(ostream& s, vector<T>& d) { REP (i, d.size()) s << d[i] << (i == d.size() - 1 ? "" : " "); return s; }
template <class T> ostream& operator<<(ostream& s, vector<vector<T>>& d) { REP (i, d.size()) s << d[i] << (i == d.size() - 1 ? "" : "\n"); return s; }
template <class T, class S> ostream& operator<<(ostream& s, pair<T, S>& p) { s << "{" << p.first << ", " << p.second << "}"; return s; }
template <class T, class S> ostream& operator<<(ostream& s, map<T, S> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
template <class T, class S> ostream& operator<<(ostream& s, unordered_map<T, S> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
#ifdef _MY_DEBUG
  #define dump(...) cerr << "/* " << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]" << endl, dump_func(__VA_ARGS__), cerr << "*/\n\n";
#else
  #define dump(...)
  #define endl "\n"
#endif
void dump_func() { cerr << endl; }
template <class Head, class... Tail> void dump_func(Head&& h, Tail&&... t) { cerr << h << (sizeof...(Tail) == 0 ? "" : ", "), dump_func(forward<Tail>(t)...); }

struct Fast { Fast() { cin.tie(0); ios::sync_with_stdio(false); } } fast;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
constexpr int MOD = 1000000007;
// *************** TEMPLATE END *************** 

template <class T>
T pow(T x, int n, const T UNION = 1) {
  T ret = UNION;
  while (n) {
    if (n & 1) ret *= x;
    x *= x; n >>= 1;
  }
  return ret;
}

template <int MD>
struct ModInt {
  int x;
  static unordered_map<int, int> to_inv;
  ModInt() : x(0) {}
  ModInt(int x_) { if ((x = x_ % MD + MD) >= MD) x -= MD; }

  ModInt& operator+=(ModInt that) { if ((x += that.x) >= MD) x -= MD; return *this; }
  ModInt& operator*=(ModInt that) { x = (unsigned long long)x * that.x % MD; return *this; }
  ModInt& operator-=(ModInt that) { if ((x -= that.x) < 0) x += MD; return *this; }
  ModInt& operator/=(ModInt that) { x = (unsigned long long)x * that.inv().x % MD; return *this; }

  ModInt operator-() const { return -x < 0 ? MD - x : -x; }
  ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
  ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
  ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
  ModInt operator/(ModInt that) const { return ModInt(*this) /= that; }
  bool operator==(ModInt that) const { return x == that.x; }
  bool operator!=(ModInt that) const { return x != that.x; }
  ModInt inv() const { return to_inv.count(this->x) ? to_inv[this->x] : (to_inv[this->x] = pow(*this, MD - 2).x); }
  friend ostream& operator<<(ostream& s, ModInt<MD> a) { s << a.x; return s; }
  friend istream& operator>>(istream& s, ModInt<MD>& a) { s >> a.x; return s; }
};
template <int MD> unordered_map<int, int> ModInt<MD>::to_inv;
using mint = ModInt<MOD>;

vector<mint> fact, fact_inv;
void init_factorial(int n) {
  fact = vector<mint>(n + 1, 1);
  fact_inv = vector<mint>(n + 1);
  for (int i = 0; i < n; i++) fact[i + 1] = fact[i] * (i + 1);
  fact_inv[n] = mint(1) / fact[n];
  for (int i = n - 1; i >= 0; i--) fact_inv[i] = fact_inv[i + 1] * (i + 1);
  // for (int i = 0; i < n + 1; i++) assert(fact[i] * fact_inv[i] == 1);
}
mint comb(int n, int r) {
  return fact[n] * fact_inv[r] * fact_inv[n - r];
}

signed main() {
  int n, K; cin >> n >> K;
  vector<vector<int>> g(n);
  REP (i, n - 1) {
    int u, v; cin >> u >> v;
    u--;
    v--;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  mint ans = K;
  function<void(int, int)> dfs = [&](int v, int p) {
    int rem = K - 1;
    if (v != 0) rem--;
    for (int s : g[v]) if (s != p) {
      ans *= rem;
      rem--;
      dfs(s, v);
    }
  };
  dfs(0, -1);
  cout << ans << endl;
}


Measured memory_bytes: 12800