#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));
using namespace std;
typedef unsigned long long ull;
typedef long long ll;

struct mint {
	long long x;
	mint(long long x = 0) :x((x% mod + mod) % mod) {}
	mint& operator+=(const mint a) {
		if ((x += a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator-=(const mint a) {
		if ((x += mod - a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator*=(const mint a) {
		(x *= a.x) %= mod;
		return *this;
	}
	mint operator+(const mint a) const {
		mint res(*this);
		return res += a;
	}
	mint operator-(const mint a) const {
		mint res(*this);
		return res -= a;
	}
	mint operator*(const mint a) const {
		mint res(*this);
		return res *= a;
	}
	mint pow(ll t) const {
		if (!t) return 1;
		mint a = pow(t >> 1);
		a *= a;
		if (t & 1) a *= *this;
		return a;
	}

	// for prime mod
	mint inv() const {
		return pow(mod - 2);
	}
	mint& operator/=(const mint a) {
		return (*this) *= a.inv();
	}
	mint operator/(const mint a) const {
		mint res(*this);
		return res /= a;
	}
};


int n, k;
vector<vector<int>> g;
vector<vector<mint>> dp;
mint res;

vector<int> in, out;
void dfs_eur(int cur, int pre, int& idx) {
	in[cur] = idx++;
	for (auto next : g[cur]) {
		if (next == pre) continue;
		dfs_eur(next, cur, idx);
	}
	out[cur] = idx;
}




void dfs1(int cur, int pre) {
	for (int i = 0; i < k; i++) dp[cur][i] = 1;
	for (auto next : g[cur]) {
		if (next == pre) continue;
		dfs1(next, cur);
		mint sum = 0;
		for (int i = 0; i < k; i++) {
			sum += dp[next][i];
			dp[cur][i] *= sum;
		}
	}

}

void dfs2(int cur, int pre) {
	{
		vector<mint> ans(k, 1);
		for (auto next : g[cur]) {
			mint sum = 0;
			if (in[cur] < in[next]) {
				for (int i = 0; i < k; i++) {
					sum += dp[next][i];
					ans[i] *= sum;
				}
			}
			else {
				ans[0] = 0;
				for (int i = 1; i < k; i++) {
					sum += dp[next][i - 1];
					ans[i] *= sum;
				}
			}
		}
		for (int i = 0; i < k; i++) res += ans[i];
	}

	vector<vector<mint>> left(k, vector<mint>(g[cur].size() + 1, 1)), right(k, vector<mint>(g[cur].size() + 1, 1));
	for (int i = 0; i < g[cur].size(); i++) {
		int next = g[cur][i];
		mint sum = 0;
		for (int j = 0; j < k; j++) {
			sum += dp[next][j];
			left[j][i + 1] = left[j][i] * sum;
		}
		
	}
	for (int i = (int)g[cur].size() - 1; i >= 0; i--) {
		int next = g[cur][i];
		mint sum = 0;
		for (int j = 0; j < k; j++) {
			sum += dp[next][j];
			right[j][i] = right[j][i + 1] * sum;
		}	
	}
	for (int i = 0; i < g[cur].size(); i++) {
		int next = g[cur][i];
		if (next == pre) continue;
		auto tmp1 = dp[cur];
		auto tmp2 = dp[next];
		for (int j = 0; j < k; j++) {
			dp[cur][j] = left[j][i] * right[j][i + 1];
		}
		mint sum = 0;
		for (int j = 0; j < k; j++) {
			sum += dp[cur][j];
			dp[next][j] *= sum;
		}
		dfs2(next, cur);
		dp[cur] = tmp1;
		dp[next] = tmp2;
	}
}
int main()
{
    /*
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    */

    scanf("%d %d", &n, &k);
    g.resize(n);
	dp = vector<vector<mint>>(n, vector<mint>(k));
    for (int i = 0; i < n - 1; i++) {
        int u, v; scanf("%d %d", &u, &v); u--; v--;
        g[u].emplace_back(v);
        g[v].emplace_back(u);
    }
	{
		in.resize(n), out.resize(n);
		int idx = 0;
		dfs_eur(0, -1, idx);
	}
	dfs1(0, -1);

	dfs2(0, -1);
	cout << res.x << "\n";
    return 0;
}