/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author edamat
 */

#include <bits/stdc++.h>

using namespace std;
#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for(int i = int(a), i##_len = (b); i < i##_len; ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define _repr(i, n) repri(i, n, 0)
/* loop in [n,m] step -1 */
#define repri(i, a, b) for(int i = int(a), i##_len = (b); i >= i##_len; --i)
/* loop in [n,0] step -1 or [n,m] step -1 */
#define repr(...) _overload3(__VA_ARGS__, repri, _repr, )(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
#define debug(x) cerr << #x << ": " << (x) << '\n'
#define pb push_back
#define eb emplace_back
//#define endl '\n'
typedef long long lint;
// #define int lint
const int INF = (int) (1 << 30) - 1;
int MOD = (int) 1e9 + 7;
//const double EPS = 1e-9;
const lint LINF = (lint) (1LL << 62) - 1;
typedef vector<int> vint;
typedef pair<int, int> pint;

struct IoSetup {
    IoSetup() {
        cin.tie(nullptr);
        ios::sync_with_stdio(false);
//        cout << fixed << setprecision(20);
//        cerr << fixed << setprecision(20);
    }
} iosetup;

using std::to_string;

auto to_string(std::string s) -> std::string {
    return '"' + s + '"';
}

auto to_string(char c) -> std::string {
    return "'" + std::string{c} + "'";
}

auto to_string(const char *s) -> std::string {
    return to_string((std::string) s);
}

auto to_string(bool b) -> std::string {
    return (b ? "true" : "false");
}

template<typename T, typename U>
auto to_string(std::pair<T, U> p) -> std::string {
    return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template<size_t N>
auto to_string(std::bitset<N> bs) -> std::string {
    std::string res{};
    for (size_t i = 0; i < N; i++)
        res.insert(res.begin(), bs.test(i) ? '1' : '0');
    return res;
}

template<typename T>
auto to_string(T v) -> std::string {
    bool flg = false;
    std::string res = "[";
    for (auto const &x : v) {
        if (flg) res += ", ";
        else flg = true;
        res += to_string(x);
    }
    res += "]";
    return res;
}

#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());
#define SZ(x) ((int)(x).size())

/* range macro. usage: for(int i:range(n)) */
class range {
private:
    struct I {
        int x;

        int operator*() { return x; }

        bool operator!=(I &lhs) { return x < lhs.x; }

        void operator++() { ++x; }
    };

    I i, n;

public:
    range(int n) : i({0}), n({n}) {}

    range(int i, int n) : i({i}), n({n}) {}

    I &begin() { return i; }

    I &end() { return n; }
};

/* keep a max,min */
template<class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}

template<class T>
bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return 1;
    }
    return 0;
}

/* input,output operator for pair and vector */
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
    os << "(" << p.first << ", " << p.second << ")";
    return os;
}

template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
    is >> p.first >> p.second;
    return is;
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "[";
    for (int i = 0; i < (int) v.size(); i++) {
        os << v[i] << (i + 1 != v.size() ? ", " : "");
    }
    os << "]";
    return os;
}

template<typename T>
istream &operator>>(istream &is, vector<T> &v) {
    for (T &in : v) is >> in;
    return is;
}

template<typename T, typename U>
ostream &operator<<(ostream &os, const map<T, U> &mp) {
    for (auto x = mp.begin(); x != mp.end(); ++x) {
        os << x->first << ": " << x->second
           << (x != prev(mp.end()) ? "\n" : "");
    }
    return os;
}

/* initialize vector. usage: auto v = male_v<int>(N,0); */
template<typename T>
vector<T> make_v(size_t a) {
    return vector<T>(a);
}

template<typename T, typename... Ts>
auto make_v(size_t a, Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}

/* fill vector. usage: fill_v(v,0); */
template<typename T, typename V>
typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) {
    t = v;
}

template<typename T, typename V>
typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) {
    for (auto &e : t) fill_v(e, v);
}

/* sum */
template<typename T>
T sum(vector<T> &v) {
    T ret = 0;
    for (T x : v) {
        ret += x;
    }
    return ret;
}

template<typename T>
auto sum(const T &a) {
    return a;
}

template<typename T, typename... A>
auto sum(const T &first, const A &... rest) {
    return sum(first) + sum(rest...);
}

/* mod */
lint intpow(lint a, lint n, lint mod) {
    lint res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

template<typename T>
T intpow(T a, lint n) {
    T res = 1;
    while (n > 0) {
        if (n & 1) res = res * a;
        a = a * a;
        n >>= 1;
    }
    return res;
}

long long modinv(long long a, long long m) {
    long long b = m, u = 1, v = 0;
    while (b) {
        long long t = a / b;
        a -= t * b;
        swap(a, b);
        u -= t * v;
        swap(u, v);
    }
    u %= m;
    if (u < 0) u += m;
    return u;
}

/* print */
template<typename T>
void print(const T &first) {
    cout << first << endl;
}

template<typename T, typename... A>
void print(const T &first, const A &... rest) {
    cout << first << " ";
    print(rest...);
}

template<typename... A>
void print(const A &... rest) {
    print(rest...);
}
struct RandomNumberGenerator {
    mt19937 mt;
    
    RandomNumberGenerator() : mt(chrono::steady_clock::now().time_since_epoch().count()) {}
    
    int operator()(int a, int b) { // [a, b)
        uniform_int_distribution<int> dist(a, b - 1);
        return dist(mt);
    }
    
    int operator()(int b) { // [0, b)
        return (*this)(0, b);
    }
};


/* Graph template */
template<typename T>
struct edge {
    int src, to;
    T cost;

    edge(int to, T cost) : src(-1), to(to), cost(cost) {}

    edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

    edge &operator=(const int &x) {
        to = x;
        return *this;
    }

    operator int() const { return to; }

    bool operator<(const edge &another) const {
        return cost < another.cost;
    };
};

template<typename T>
using Edges = vector<edge<T>>;
template<typename T>
using WeightedGraph = vector<Edges<T>>;
using UnWeightedGraph = vector<vector<int>>;
template<typename T>
using Matrix = vector<vector<T>>;


/* Modint */
template <typename T, T MOD = 1000000007>
struct ModInt {
    static constexpr T mod = MOD;
    T v;
    ModInt() : v(0) {}
    ModInt(signed v) : v(v) {}
    ModInt(long long t) {
        v = t % MOD;
        if(v < 0) v += MOD;
    }

    ModInt pow(long long k) {
        ModInt res(1), tmp(v);
        while(k) {
            if(k & 1) res *= tmp;
            tmp *= tmp;
            k >>= 1;
        }
        return res;
    }

    static ModInt add_identity() { return ModInt(0); }
    static ModInt mul_identity() { return ModInt(1); }

    ModInt inv() { return pow(MOD - 2); }

    ModInt &operator+=(ModInt a) {
        v += a.v;
        if(v >= MOD) v -= MOD;
        return *this;
    }
    ModInt &operator-=(ModInt a) {
        v += MOD - a.v;
        if(v >= MOD) v -= MOD;
        return *this;
    }
    ModInt &operator*=(ModInt a) {
        v = 1LL * v * a.v % MOD;
        return *this;
    }
    ModInt &operator/=(ModInt a) { return (*this) *= a.inv(); }

    ModInt operator+(ModInt a) const { return ModInt(v) += a; };
    ModInt operator-(ModInt a) const { return ModInt(v) -= a; };
    ModInt operator*(ModInt a) const { return ModInt(v) *= a; };
    ModInt operator/(ModInt a) const { return ModInt(v) /= a; };

    ModInt operator-() const { return v ? ModInt(MOD - v) : ModInt(v); }

    bool operator==(const ModInt a) const { return v == a.v; }
    bool operator!=(const ModInt a) const { return v != a.v; }
    bool operator<(const ModInt a) const { return v < a.v; }

    // find x s.t. a^x = b
    static T log(T a, T b) {
        const T sq = 40000;
        unordered_map<T, T> dp;
        dp.reserve(sq);
        ModInt res(1);
        for(int r = 0; r < sq; r++) {
            if(!dp.count(res.v)) dp[res.v] = r;
            res *= a;
        }
        ModInt p = ModInt(a).inv().pow(sq);
        res = b;
        for(int q = 0; q <= MOD / sq + 1; q++) {
            if(dp.count(res.v)) {
                T idx = q * sq + dp[res.v];
                if(idx > 0) return idx;
            }
            res *= p;
        }
        assert(0);
        return T(-1);
    }

    static ModInt comb(long long n, int k) {
        ModInt num(1), dom(1);
        for(int i = 0; i < k; i++) {
            num *= ModInt(n - i);
            dom *= ModInt(i + 1);
        }
        return num / dom;
    }
};
template <typename T, T MOD>
constexpr T ModInt<T, MOD>::mod;
template <typename T, T MOD>
ostream &operator<<(ostream &os, ModInt<T, MOD> m) {
    os << m.v;
    return os;
}



template<typename T>
struct Combination {
    vector <T> _fact, _rfact;
    
    Combination(int sz) : _fact(sz + 1), _rfact(sz + 1) {
        _fact[0] = _rfact[sz] = 1;
        for(int i = 1; i <= sz; i++) _fact[i] = _fact[i - 1] * i;
        _rfact[sz] /= _fact[sz];
        for(int i = sz - 1; i >= 0; i--) _rfact[i] = _rfact[i + 1] * (i + 1);
    }
    
    inline T fact(int k) const { return _fact[k]; }
    
    inline T rfact(int k) const { return _rfact[k]; }
    
    T P(int n, int r) const {
        if(r < 0 || n < r) return 0;
        return fact(n) * rfact(n - r);
    }
    
    T C(int p, int q) const {
        if(q < 0 || p < q) return 0;
        return fact(p) * rfact(q) * rfact(p - q);
    }
    
    T H(int n, int r) const {
        if(n < 0 || r < 0) return (0);
        return r == 0?1:C(n + r - 1, r);
    }
};


class EVirusTree2 {
public:
    static constexpr int kStressIterations = 0;
    
    static void generateTest(int cnt, std::ostream &test) {
        RandomNumberGenerator rg;
    }
    
    using modint = ModInt<int, 1000000007>;
    modint ret;
    
    void dfs(Combination<modint> &comb, int K, const UnWeightedGraph &G, int v, int p) {
        int com_left;
        int cnt = 0;
        if(p == -1){
            com_left = K - 1;
        } else {
            com_left = K - 2;
        }
        for(auto nv : G[v]){
            if(nv == p)continue;
            cnt++;
            dfs(comb, K, G, nv, v);
        }
        ret *= comb.P(com_left, cnt);
    }
    
    void solve(std::istream &cin, std::ostream &cout) {
        Combination<modint> comb(100005);
        ret = 1;
        int N, K;
        cin >> N >> K;
        UnWeightedGraph tree(N);
        rep(i, N - 1){
            int a, b;
            cin >> a >> b;
            a--;
            b--;
            tree[a].pb(b);
            tree[b].pb(a);
        }
        dfs(comb, K, tree, 0, -1);
        cout << ret * K << endl;
    }
};


int main() {
	EVirusTree2 solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 9728