#include <cstdio>
#include <vector>
#define MODD 1000000007ULL
using namespace std;
int n,k;
vector<int> v[100005];
       int col[100005];
      bool us[100005];
unsigned long long int ans=1;
void BF(int nr){
    us[nr]=1;
    for(int i=col[nr]-v[nr].size()+1;i<=col[nr];i++)
        ans=(ans*i)%MODD;
    for(unsigned int i=0;i<v[nr].size();i++){
        if(!us[i]){
            col[i]--;
            BF(i);
        }
    }
}
int main(){
    freopen("colorare3.in","r",stdin);
    freopen("colorare3.out","w",stdout);
    int x,y;
    scanf("%d%d",&n,&k);
    for(int i=0;i<n-1;i++){
        scanf("%d%d",&x,&y);
        //fr[x]++;fr[y]++;
        v[x].push_back(y);v[y].push_back(x);
        col[i]=k;
    }
    BF(1);
    printf("%llu",ans);
    return 0;
}