#include <bits/stdc++.h>
using namespace std;
using LL = long long;

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 (b<a) { a=b; return 1; } return 0; }


// std::vector Declaration
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...));
}

// std::vector Initialization
template<typename T>
void fill_all(T& arr, const T& v) { arr = v; }
template<typename T, typename U>
void fill_all(T& arr, const U& v) { for (auto& i : arr) fill_all(i, v); }

// std::vector Debug
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v ) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::pair Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << "(" << p.first << " " << p.second << ")";
    return os;
}

// std::set Debug
template<typename T>
ostream& operator<<(ostream& os, const set<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::multiset Debug
template<typename T>
ostream& operator<<(ostream& os, const multiset<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::map Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const map<T, U>& mp) {
    os << "{";
    bool a = 1;
    for (auto e : mp) {
        os << (a ? "" : " ");
        os << e.first << ":" << e.second;
        a = 0;
    }
    os << "}";
    return os;
}

// std::tuple Debug
template<int N, class Tuple>
void out(ostream& os, const Tuple& t){}
template<int N, class Tuple, class H, class ...Ts>
void out(ostream& os, const Tuple& t) {
    if (N) os << " ";
    os << get<N>(t);
    out<N+1,Tuple,Ts...>(os, t);
}
template<class ...Ts>
ostream& operator<<(ostream& os, const tuple<Ts...>& t) {
    os << "(";
    out<0,tuple<Ts...>,Ts...>(os, t);
    os << ")";
    return os;
}

// Debug
#define DUMP(x) cerr<<#x<<" = "<<(x)<<endl


struct edge { int to, cost; };
ostream& operator<<(ostream& os, const edge& e) {
    os << "(" << e.to << ", " << e.cost << ")";
    return os;
}

const LL LINF = 1LL<<60;
const int IINF = 1<<30;
const LL MOD = 1e9+7;

template<typename T, T mod>
struct ModInt {
    T val;
    ModInt(T val=0) : val(((val % mod) + mod) % mod) {}

    const ModInt operator+() const { return *this; }
    const ModInt operator-() const { return (-val + mod) % mod; }
    const ModInt reciprocal() const { return power(mod-2); }

    ModInt& operator+=(const ModInt& rhs) { (val += rhs.val) %= mod; return *this; }
    ModInt& operator-=(const ModInt& rhs) { return *this += -rhs; }
    ModInt& operator*=(const ModInt& rhs) { (val *= rhs.val) %= mod; return *this; }
    ModInt& operator/=(const ModInt& rhs) { return *this *= rhs.reciprocal(); }

    const ModInt operator+(const ModInt& rhs) const { return ModInt(*this) += rhs; }
    const ModInt operator-(const ModInt& rhs) const { return ModInt(*this) -= rhs; }
    const ModInt operator*(const ModInt& rhs) const { return ModInt(*this) *= rhs; }
    const ModInt operator/(const ModInt& rhs) const { return ModInt(*this) /= rhs; }

    const ModInt power(long long n) const {
        ModInt ret = 1, tmp = val;
        while (n > 0) {
            if (n & 1) ret *= tmp;
            tmp *= tmp;
            n >>= 1;
        }
        return ret;
    }

    bool operator==(const ModInt& rhs) const { return val == rhs.val; }
    bool operator!=(const ModInt& rhs) const { return !(*this == rhs); }
};

template<typename T, T mod>
const ModInt<T, mod> operator+(const T& lhs, const ModInt<T, mod>& rhs) {
    return ModInt<T, mod>(lhs) + rhs;
}
template<typename T, T mod>
const ModInt<T, mod> operator-(const T& lhs, const ModInt<T, mod>& rhs) {
    return ModInt<T, mod>(lhs) - rhs;
}
template<typename T, T mod>
const ModInt<T, mod> operator*(const T& lhs, const ModInt<T, mod>& rhs) {
    return ModInt<T, mod>(lhs) * rhs;
}
template<typename T, T mod>
const ModInt<T, mod> operator/(const T& lhs, const ModInt<T, mod>& rhs) {
    return ModInt<T, mod>(lhs) / rhs;
}

template<typename T, T mod>
bool operator==(const T& lhs, const ModInt<T, mod>& rhs) {
    return ModInt<T, mod>(lhs) == rhs;
}
template<typename T, T mod>
bool operator!=(const T& lhs, const ModInt<T, mod>& rhs) {
    return ModInt<T, mod>(lhs) != rhs;
}

template<typename T, T mod>
auto& operator<<(ostream& s, const ModInt<T, mod>& obj) { s << obj.val; return s; }

using GF = ModInt<LL, MOD>;

int n, k;
vector<vector<int>> G;

GF dfs(int v, int p) {
    GF prod = 1;
    for (auto u : G[v]) {
        if (u == p) continue;
        prod *= dfs(u, v);
    }

    if (p == -1) {
        for (int i = 1; i <= G[v].size(); ++i) {
            prod *= (k - i);
        }
    }
    else {
        for (int i = 1; i <= G[v].size()-1; ++i) {
            prod *= (k - i - 1);
        }
    }
    return prod;
}

int main()
{
    cin >> n >> k;
    G.resize(n, vector<int>());
    for (int i = 0; i < n-1; ++i) {
        int a, b; cin >> a >> b;
        --a; --b;
        G[a].push_back(b);
        G[b].push_back(a);
    }

    GF ans = dfs(0, -1) * k;
    cout << ans << endl;

    return 0;
}


Measured memory_bytes: 11520