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

#define NMAX 100001
#define MOD 1000000007
#define DIM 10000

vector <int> v[NMAX];
int viz[NMAX],k,sol,poz;
char buff[DIM+1];

void citeste(int &numar)
{
    while(buff[poz]<'0' || buff[poz]>'9')
        if(++poz==DIM) {
            fread(buff,1,DIM,stdin);
            poz=0;
        }
    numar=0;
    while(buff[poz]>='0' && buff[poz]<='9') {
        numar=numar*10+buff[poz]-'0';
        if(++poz==DIM) {
            fread(buff,1,DIM,stdin);
            poz=0;
        }
    }
}

void dfs(int nod, int less)
{
    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;
    freopen("colorare3.in","r",stdin);
    ofstream g("colorare3.out");
    citeste(n);
    citeste(k);
    for(i=1;i<=n-1;i++) {
        citeste(x);
        citeste(y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    fclose(stdin);
    sol=1;
    dfs(1,0);
    g<<sol;
    g.close();
    return 0;
}