#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
#include <cstdio>
#include <string>
#include <cmath>
#include <queue>
#include <tuple>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <random>
#include <set>
#include <stack>
#include <time.h>

//#include <bits/stdc++.h>
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define repr(i, n) for (int i = (n) - 1; i >= 0; i--)
#define FOR(i,i0,n) for(int (i)=(i0);(i)<(n);(i)++)
#define FORR(i,i0,n) for(int (i)=(n)-1; (i)>=(i0);(i)--)
#define SORT(x) sort(x.begin(),x.end())
#define SORTR(x) sort(x.begin(),x.end(),greater<vector<int>>())
#define rn return
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple

using namespace std;
using ll = long long;
typedef std::pair<int, int> pii;
typedef std::pair<int, double> pid;
typedef std::vector<int> vi;
typedef std::vector<pii> vii;

#define PI 3.14159265358979323846264338327950L
const int mod = 1000000007;

struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
 
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};

istream& operator>>(istream& is, const mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}

struct combination {
  vector<mint> fact, ifact;
  combination(int n):fact(n+1),ifact(n+1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n) return 0;
    return fact[n]*ifact[k]*ifact[n-k];
  }
};


vector<vector<int>> g;
mint ans;
combination comb = combination(100100);
int n,k;

void dfs(int node, int parent){
    for(auto ne:g[node]){
        if (parent == ne) continue;
        dfs(ne,node);
    }
    int children = g[node].size();
    if (parent == -1) ans *= comb(k,children+1)*comb.fact[children+1];
    else ans *= comb(k-2,children-1)*comb.fact[children-1];
}

void solve(){
    
    cin >> n >> k;
    g.resize(n);
    
    rep(i,n-1){
        int a,b;
        cin >> a >> b;
        a--,b--;
        g[a].pb(b);
        g[b].pb(a);
    }
    
    ans = 1;
    dfs(0,-1);
    cout << ans;
}


int main() {
    int T;
    //cin >> T;
    T = 1;
    while (T--) {
        solve();
        cout << endl;
    }
}














Measured memory_bytes: 13640