#include <bits/stdc++.h>

using namespace std;

const int nmax = 1e5;
int n, k;
vector<int>g[nmax + 1];
const int mod = 1e9 + 7;

void cit(int &x) {
  x = 0;
  char c = getchar();

  while (!isdigit(c))
    c = getchar();

  while (isdigit(c))
    x = x * 10 + c - '0', c = getchar();
}

int dfs(int node, int father) {
  int sol = 1, nr;

  if (node == 1)
    nr = k;
  else nr = k - 1;

  for (auto i : g[node]) {
    if (i == father)
      continue;

    sol = (1LL * sol * nr) % mod;
    sol = (1LL * sol * dfs(i, node)) % mod;
    nr--;
  }

  return sol;
}
int main() {
  freopen("colorare3.in", "r", stdin);
  freopen("colorare3.out", "w", stdout);
  cit(n);
  cit(k);

  for (int i = 1; i < n; ++i) {
    int x, y;
    cit(x), cit(y);
    g[x].push_back(y);
    g[y].push_back(x);
  }
  printf("%d",dfs(1,0));
}