// 解説AC(たぶん)
#include<bits/stdc++.h>
using namespace std;using ll=long long;using vi=vector<int>;using vvi=vector<vi>;using vl=vector<ll>;using vvl=vector<vl>;using P=pair<int,int>;using PL=pair<ll,ll>;using vp=vector<P>;using vpl=vector<PL>;
template<typename T>constexpr auto inf=numeric_limits<T>::max()/2;constexpr int INF=inf<int>,MOD=1000000007;constexpr ll LINF=inf<ll>;
#define _ol3(_1,_2,_3,name,...)name
#define _rep(i,n)_repi(i,0,n)
#define _repi(i,a,b)for(int i=a,i##_l=(b);i<i##_l;++i)
#define REP(...)_ol3(__VA_ARGS__,_repi,_rep,)(__VA_ARGS__)
#define REPR(i,n)for(int i=n-1;i>=0;--i)
#define REPA(i,v)REP(i,(v).size())
#define all(v)(v).begin(),(v).end()
#define rall(v)(v).rbegin(),(v).rend()
#define bit(n)(1ll<<(n))
#define F first
#define S second
#define endl '\n'
#define cho(n,a,b)cout<<((n)?a:b)<<endl
void YES(int n){cho(n,"YES","NO");}void Yes(int n){cho(n,"Yes","No");}void Poss(int n){cho(n,"Possible","Impossible");}
void _print(ostream&){}template<class T,class...U>void _print(ostream&s,const T&t,const U&...u){s<<t<<(sizeof...(u)?' ':'\n');_print(s,u...);}
template<class...T>void print(const T&...t){_print(cout,t...);}template<class...T>void dprint(const T&...t){_print(cerr,t...);}
#ifndef LOCAL
struct osd{template<class T>osd&operator<<(const T&t){return*this;}};osd cer_;
#define dprint(...)
#define cerr cer_
#endif
template<class T>bool chmax(T&a,const T&b){bool x=a<b;x?a=b:b;return x;}template<class T>bool chmin(T&a,const T&b){bool x=a>b;x?a=b:b;return x;}
template<class T,class U>ostream&operator<<(ostream&o,const pair<T,U>&p){return o<<p.F<<' '<<p.S;}
template<class T,class U>istream&operator>>(istream&i,pair<T,U>&p){return i>>p.F>>p.S;}
template<class T>class iterable{static false_type c(string v);template<class U>static auto c(U v)->decltype(all(v),true_type());static false_type c(...);public:const static bool value=decltype(c(declval<T>()))::value;};
template<class T,typename=enable_if_t<iterable<T>::value>>ostream&operator<<(ostream&o,const T&v){for(auto&&i:v)o<<i<<' ';return o;}
template<class T>istream&operator>>(istream&i,vector<T>&v){for(T&j:v)i>>j;return i;}
template<class T>vector<T>&operator<<(vector<T>&v,const T&t){v.push_back(t);return v;}
template<class T>set<T>&operator<<(set<T>&v,const T&t){v.insert(t);return v;}
template<class T>multiset<T>&operator<<(multiset<T>&v,const T&t){v.insert(t);return v;}
template<ll MODULO=MOD> // modulo should be prime
class mint{
    static_assert(MODULO>0, "modulo should be positive");
private:
    ll a;
    constexpr static ll _nl(const ll&a){return a>=0?a%MODULO:MODULO-(-a-1)%MODULO-1;}
public:
    constexpr static ll phi() {
        ll ans=MODULO;
        ll nn=MODULO;
        for (ll x = 2; x*x <= nn; ++x) {
            if (nn % x == 0) {
                ans -= ans / x;
                while (nn % x == 0) nn /= x;
            }
        }
        if (nn > 1) ans -= ans / nn;
        return ans;
    }
    mint():a(0){}
    mint(const ll&a):a(_nl(a)){}
    mint(const mint&o):a((ll)o){}

    inline mint&operator=(const ll&o){a=_nl(o);return*this;};
    inline operator ll()const{return a;}
    inline operator bool()const{return (bool)a;}

    inline mint&operator+=(const ll&o){a=_nl(a+_nl(o));return*this;};
    inline mint&operator-=(const ll&o){a=_nl(a+_nl(-o));return*this;};
    inline mint&operator*=(const ll&o){a=_nl(a*_nl(o));return*this;};
    inline mint&operator/=(const ll&o){a=_nl(a*_nl(mint(o)^(phi()-1)));return*this;}
    inline mint&operator%=(const ll&o){a=_nl(a%_nl(o));return*this;};
    inline mint&operator^=(const mint<phi()>&o){
        ll _o=(ll)o;
        if(_o==0){a=1;return*this;}
        if(_o==1)return *this;
        if(_o==2)return *this*=a;
        ll aa=a;
        *this^=(_o/2);
        *this*=a;
        if(_o%2)*this*=aa;
        return*this;
    }

    const mint operator+(const ll&o)const{mint b(a);return b+=o;}
    const mint operator-(const ll&o)const{mint b(a);return b-=o;}
    const mint operator*(const ll&o)const{mint b(a);return b*=o;}
    const mint operator/(const ll&o)const{mint b(a);return b/=o;}
    const mint operator%(const ll&o)const{mint b(a);return b%=o;}
    const mint operator^(const ll&o)const{mint b(a);return b^=o;}

    inline const mint operator+()const{return *this;}
    inline const mint operator-()const{return mint(-a);}
};

template<ll M>ostream&operator<<(ostream&o,const mint<M>&v){return o<<(ll)v;}
template<ll M>istream&operator>>(istream&i,mint<M>&v){ll b;i>>b;v=b;return i;}
inline ll square(ll a){a%=MOD;return (a*a)%MOD;}
ll lpow(ll a,ll b){
    a%=MOD;
    b%=MOD-1;
    if(b==0)return 1;
    if(b==1)return a;
    if(b%2){
        return (square(lpow(a,b/2)%MOD)*a)%MOD;
    }else{
        return square(lpow(a,b/2)%MOD);
    }
}

ll fact(ll n){
    ll ans=1;
    while(n){
        ans=(ans*n--)%MOD;
    }
    return ans;
}

ll factto(ll a,ll b){
    ll ans=1;
    for(ll i=a;i<=b;i++){
        ans=(ans*i)%MOD;
    }
    return ans;
}

ll perm(ll n,ll r){ // nPr
    return factto(n-r+1,n)%MOD;
}

ll comb(ll n,ll r){ // nCr
    return (perm(n,r)*lpow(fact(r),MOD-2))%MOD;
}

ll homo(ll n,ll r){ // nHr
    return comb(n+r-1,r);
}
int main(){
    cin.tie(0);ios::sync_with_stdio(0);
    cout<<setprecision(10);
    int n,k;
    cin>>n>>k;
    vvi e(n);
    REP(i,n-1){
        int a,b;
        cin>>a>>b;
        --a;--b;
        e[a].push_back(b);
        e[b].push_back(a);
    }
    mint<> ans(k);
    queue<P> q;
    q.push({0,0});
    while(q.size()){
        int t=q.front().F;
        int r=q.front().S;
        q.pop();
        ans*=perm(k-1-(!!t),e[t].size()-(!!t));
        dprint('*',perm(k-1-(!!t),e[t].size()));
        for(int d:e[t])if(d!=r)q.push({d,t});
    }
    cout<<ans<<endl;
}


Measured memory_bytes: 6904