#include <bits/stdc++.h>
using namespace std;
using i64 = int_fast64_t;
#define repeat(i, a, b) for(int i = (a); (i) < (b); ++(i))
#define rep(i, n) repeat(i, 0, n)

#define mygc(c) (c) = getchar_unlocked()
#define mypc(c) putchar_unlocked(c)
// usage: i64 x=rd()
template <typename T = i64>
inline T rd() {
    T x = 0, m = 0, k;
    for(;;) {
        mygc(k);
        if(k == '-') {
            m = 1;
            break;
        }
        if('0' <= k && k <= '9') {
            x = k - '0';
            break;
        }
    }
    for(;;) {
        mygc(k);
        if(k < '0' || '9' < k) break;
        x = x * 10 + k - '0';
    }
    return x;
}
template <typename T = i64>
inline std::vector<T> rd(int N) {
    std::vector<T> ret(N);
    for(int i = 0; i < N; i++) {
        ret[i] = rd();
    }
    return ret;
}
// usage: wr(x);
template <typename T = i64>
void wr(T x, char c = '\n') {
    int s = 0, m = 0;
    char b[64];
    if(x < 0) m = 1, x = -x;
    for(; x; x /= 10) b[s++] = x % 10;
    if(!s) b[s++] = 0;
    if(m) mypc('-');
    for(; s--;) mypc(b[s] + '0');
    mypc(c);
}
template <typename T = i64, class... Args>
void wr(T&& a, Args&&... args) {
    wr(a, ' ');
    wr(std::forward<Args>(args)...);
    return;
}
template <typename T = i64>
void wr(std::vector<T>& a) {
    for(int i = 0; i < a.size(); i++) {
        i != a.size() - 1 ? wr(a[i], ' ') : wr(a[i], '\n');
    }
    return;
}

namespace edamat {
// modint: mod 計算を int を扱うように扱える構造体
template <int MOD>
struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if(val < 0) val += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator-() const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator+(const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator-(const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator*(const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator/(const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator+=(const Fp& r) noexcept {
        val += r.val;
        if(val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator-=(const Fp& r) noexcept {
        val -= r.val;
        if(val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator*=(const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator/=(const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while(b) {
            long long t = a / b;
            a -= t * b;
            swap(a, b);
            u -= t * v;
            swap(u, v);
        }
        val = val * u % MOD;
        if(val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator==(const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator!=(const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator<<(ostream& os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr istream& operator>>(istream& is, Fp<MOD>& x) noexcept {
        return is >> x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD>& a, long long n) noexcept {
        if(n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if(n & 1) t = t * a;
        return t;
    }
};

// 二項係数ライブラリ
template <class T>
struct BiCoef {
    vector<T> fact_, inv_, finv_;
    constexpr BiCoef() {}
    constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
        init(n);
    }
    constexpr void init(int n) noexcept {
        fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
        int MOD = fact_[0].getmod();
        for(int i = 2; i < n; i++) {
            fact_[i] = fact_[i - 1] * i;
            inv_[i] = -inv_[MOD % i] * (MOD / i);
            finv_[i] = finv_[i - 1] * inv_[i];
        }
    }
    constexpr T com(int n, int k) const noexcept {
        if(n < k || n < 0 || k < 0) return 0;
        return fact_[n] * finv_[k] * finv_[n - k];
    }
    constexpr T fact(int n) const noexcept {
        if(n < 0) return 0;
        return fact_[n];
    }
    constexpr T inv(int n) const noexcept {
        if(n < 0) return 0;
        return inv_[n];
    }
    constexpr T finv(int n) const noexcept {
        if(n < 0) return 0;
        return finv_[n];
    }
};
}  // namespace edamat

const int MOD = 1000000007;
using modint = edamat::Fp<MOD>;
edamat::BiCoef<modint> bc;

int N, K;
vector<vector<int>> G;

void rec(int v, int p, modint& res, int depth) {
    int chs = 0;
    for(auto ch : G[v]) {
        if(ch == p) continue;
        ++chs;
        rec(ch, v, res, depth + 1);
    }
    if(depth == 0)
        res *= bc.com(K - 1, chs) * bc.fact(chs);
    else
        res *= bc.com(K - 2, chs) * bc.fact(chs);
}

int main() {
    bc.init(110000);
    N = rd(), K = rd();
    G.assign(N, vector<int>());
    for(int i = 0; i < N - 1; ++i) {
        int a, b;
        a = rd(), b = rd();
        --a, --b;
        G[a].push_back(b);
        G[b].push_back(a);
    }
    modint res = 1;
    rec(0, -1, res, 0);
    printf("%d\n", res * K);
}

Measured memory_bytes: 14208