#include<iostream>
#include<fstream>
#include<vector>
using namespace std;

#define NMAX 100001
#define MOD 1000000007

vector <int> v[NMAX];
int viz[NMAX],k,sol;

void dfs(int nod, int less)
{
	int nr;
	viz[nod]=1;
	for(vector <int> :: iterator it=v[nod].begin();it!=v[nod].end();it++)
		if(viz[*it]==0) {
			sol=(1LL*sol*(k-less))%MOD;
			less++;
			dfs(*it,1);
		}
	
}

int main ()
{
	int n,x,y,i;
	ifstream f("colorare3.in");
	ofstream g("colorare3.out");
	f>>n>>k;
	for(i=1;i<=n-1;i++) {
		f>>x>>y;
		v[x].push_back(y);
		v[y].push_back(x);
	}
	f.close();
	sol=1;
	dfs(1,0);
	g<<sol;
	g.close();
	return 0;
}