#include "bits/stdc++.h"

using namespace std;
#define ll long long
#define endl '\n'
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rep2(i,a,b) for(int i=int(a);i<int(b);i++)
#define pb push_back
#define all(x) (x).begin(),(x).end()
int mod=1e9+7;
int mod2=998244353;
const int INF=1e9;

vector<ll> G[int(1e5+1)];
ll ans=1;
ll deep=0;

ll n,k;
vector<ll> used(1e5+1,0);

void dfs(ll np,ll x){
    ll tmp=0;
    // rep(i,G[np].size()){
    //     if(used[G[np][i]]==1)tmp++;
    //     rep(j,G[G[np][i]].size()){
    //         if(used[G[G[np][i]][j]]==1)tmp++;
    //     }
    // }

    if(deep==0)tmp=0;
    else if(deep==1){
        tmp=x+1;
    }else tmp=x+2;

    //cout<<np<<" "<<tmp<<" "<<x<<endl;

    used[np]=1;
    ans*=(k-tmp);
    ans%=mod;

    ll y=0;
    rep(i,G[np].size()){
        if(used[G[np][i]]==0){
            deep++;
            dfs(G[np][i],y);
            y++;
            deep--;
        }
    }
}

signed main(){
    cin>>n>>k;
    rep(i,n-1){
        ll a,b;
        cin>>a>>b;
        a--;
        b--;
        G[a].pb(b);
        G[b].pb(a);
    }
    
    dfs(0,0);
    cout<<ans<<endl;
}

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