#include <fstream>

using namespace std;

ifstream in("colorare3.in");
ofstream out("colorare3.out");

const int M=1000000007;
long long n,k,f[100005],sol,p,a,b;

void rez()
{
	in>>n>>k;
	for(int i=1;i<=n-1;++i)
	{
		in>>a>>b;
		++f[a];++f[b];
	}
	sol=1;
	for(int i=1;i<=n;++i)
	{
		p=k-1+(i==1);
		for(int j=k-f[i]+1;j<=p;++j)
			sol=(sol*j)%M;
	}
	out<<sol;
}
int main()
{
	rez();
	return 0;
}