#include<cstdio>
#include<vector>
using namespace std;
const int N=100005;
const int MOD=1000000007;
vector<int> v[N],fiu[N];
bool f[N];
int n,k;
long long prod;
void df(int nod)
{
    for(vector<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
        if(!f[*it])
        {
            f[*it]=true;
            fiu[nod].push_back(*it);
            df(*it);
        }
}
void dfs(int nod)
{
    int q=k-1;
    for(vector<int>::iterator it=fiu[nod].begin();it!=fiu[nod].end();it++)
    {
        prod=(long long)prod*q%MOD;
        --q;
        dfs(*it);
    }
}
int main()
{
    freopen("colorare3.in","r",stdin);
    freopen("colorare3.out","w",stdout);
    scanf("%d%d",&n,&k);
    int x,y;
    for(int i=1;i<n;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    f[1]=true;
    df(1);
    int q=k;
    prod=1;
    for(vector<int>::iterator it=fiu[1].begin();it!=fiu[1].end();it++)
    {
        prod=(long long)prod*q;
        prod%=MOD;
        --q;
        dfs(*it);
    }
    printf("%lld",prod);
    return 0;
}