#include <stdio.h>
#include <vector>
#define NMAX 100005
#define pb push_back
#define MOD 1000000007
#define ll long long
using namespace std;
int n,k,fii[NMAX];
vector <int> A[NMAX];
ll pos[NMAX],rez;
char viz[NMAX];
void read()
{
	scanf("%d%d",&n,&k);
	int i,x,y;
	for (i=1; i<n; i++)
	{
		scanf("%d%d",&x,&y);
		A[x].pb(y);
		A[y].pb(x);
	}
}
void dfs(int nod)
{
	viz[nod]=1;
	int i,vec;
	for (i=0; i<A[nod].size(); i++)
	{
		vec=A[nod][i];
		if (!viz[vec])
		{
			fii[nod]++;
			dfs(vec);
		}
	}
}
ll aranj(int a,int b)
{
	int i;
	ll act=1;
	for (i=a-b+1; i<=a; i++)
	{
		act*=i;
		if (act>=MOD)
			act%=MOD;
	}
	return act;
}
void solve()
{
	int i;
	pos[1]=aranj(k,fii[1]);
	rez=pos[1];
	for (i=2; i<=n; i++)
	{
		pos[i]=aranj(k-1,fii[i]);
		rez*=pos[i];
		if (rez>=MOD)
			rez%=MOD;
	}
}
int main()
{
	freopen("colorare3.in","r",stdin);
	freopen("colorare3.out","w",stdout);
	read();
	dfs(1);
	solve();
	printf("%lld\n",rez);
	return 0;
}