#include <bits/stdc++.h>
#define REP(i, n)     for(int i = 0;i < n;i++)
#define REPR(i, n)    for(int i = n;i >= 0;i--)
#define FOR(i, m, n)  for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define VRSORT(v) sort(v.begin(), v.end(),greater<int>());
#define ALL(X) (X).begin(),(X).end()
#define INF 99999999
#define M_PI 3.14159265358979323846
#define MOD 1000000007

#ifdef __LOCAL
    #define DBG(X) cout << #X << " = " << (X) << endl;
    #define SAY(X) cout << (X) << endl;
#else
    #define DBG(X)
    #define SAY(X)
#endif

#ifdef __LOCAL
    #include <filesystem>
    namespace fs = std::filesystem;
#endif

using namespace std;

using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

int dx[]={1, 0, -1, 0, 0};
int dy[]={0, 1, 0, -1, 0};
const int INT_INF = (int)(2e9);
const ll  LL_INF = (ll)(2e18);
const int NIL = -1;
static mt19937 _g(time(nullptr));
 
std::string pad(int num){ char buffer[4]; std::snprintf(buffer, sizeof(buffer), "%03d", num); return buffer;}
inline ll randint(ll a, ll b) { ll w = (_g() << 31LL) ^ _g(); return a + w % (b - a + 1); }
inline void fast_io() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); };
template<typename T> inline T sign(T x) { return T(x > 0) - T(x < 0); }
template<typename T, typename S> inline ostream& operator<<(ostream& os, const pair<T, S> p) { cout << "[" << p.first << ";" << p.second << "]"; return os; }
template<typename T> inline ostream& operator<<(ostream& os, const vector<T>& v) { for (auto el : v) os << el << " "; return os; }
template<typename T> inline T fetch() { T ret; cin >> ret; return ret; }
template<typename T> inline vector<T> fetch_vec(int sz) { vector<T> ret(sz); for (auto& elem : ret) cin >> elem; return ret; }


int N,K;
// vector<int> A,B;
map<int,vector<int> > toList;
map<int,vector<int> > totoList;

void input(){
  #ifdef __LOCAL
      fs::path p = __FILE__;
      fs::path input,output;
      input = output = p.parent_path();
      input += string("/input/") + string(p.stem()) + string(".txt");
      output += string("/output/") + string(p.stem()) + string(".txt");
      freopen(input.c_str(), "r", stdin);
      freopen(output.c_str(), "w", stdout);
  #endif

  fast_io();
  cin >> N >> K;
  // A.assign(N-1,0);
  // B.assign(N-1,0);
  for (int i = 0;i < N-1;i++)
  {
    int a,b;
    // cin >> A[i] >> B[i];
    cin >> a >> b;
    a--;b--;
    // A[i]--;
    // B[i]--;
    // toList[A[i]].push_back(B[i]);
    // toList[B[i]].push_back(A[i]);
    toList[a].push_back(b);
    toList[b].push_back(a);
  }
  // for (int i = 0; i < N; i++)
  // {
  //   for(auto x:toList[i]) {
  //     totoList[i].push_back(x);
  //     for(auto y:toList[x]) if(y!=i) totoList[i].push_back(y);
  //     }
  // }
  
}

// TLEがでてダメだった。WAもいくつかあった。
vector<bool> visited;
map<pii,ll> memo;
ll bfs(int node, int parent){
  if(memo[{node,parent}]!=0) return memo[{node,parent}];
  ll ans=K;
  visited[node]=true;
  if(parent==-1) {
    for(auto x:toList[node]) if(!visited[x]) ans=ans*bfs(x,node)%MOD;
    return memo[{node,parent}] = ans%MOD;
    }
  else{
    for(auto x:toList[parent]) ans-=visited[x];
    if(ans<=0LL) return 0LL;
    for(auto x:toList[node]) if(!visited[x]) ans=ans*bfs(x,node)%MOD;
    return memo[{node,parent}] = ans%MOD;
  }
}

// TLE
int solve(){
  visited.assign(N,false);
  // cout << bfs(0,-1) << endl;
  vector<int> dp;
  vector<int> parentEdge;
  dp.assign(N,0);
  parentEdge.assign(N,0);
  int i,p;
  queue<pii> q;
  q.push({0,-1});
  dp[0] = K;
  while(!q.empty())
  {
    tie(i,p) = q.front();
    q.pop();
    visited[i]=true;
    if(p!=-1) {dp[i]=K; parentEdge[p]++; dp[i] -= parentEdge[p]; parentEdge[i]++;}
    // for(auto x:toList[p]) if(visited[x]) dp[i]--;
    for(auto x:toList[i]) if(!visited[x]) q.push({x,i});
  }
  ll ans=1;
  for (int i = 0; i < N; i++)
  {
    ans=(ans*dp[i])%MOD;
  }
  cout << ans%MOD << endl;
  

  return 0;
}

int main()
{
  input();
  solve();
  return 0;
}


Measured memory_bytes: 13176