You are given a tree (a connected undirected graph without cycles) of n vertices. Each of the n - 1 edges of the tree is colored in either black or red.

You are also given an integer k. Consider sequences of k vertices. Let's call a sequence [a_1, a_2, …, a_k] good if it satisfies the following criterion:

  * We will walk a path (possibly visiting same edge/vertex multiple times) on the tree, starting from a_1 and ending at a_k. 
  * Start at a_1, then go to a_2 using the shortest path between a_1 and a_2, then go to a_3 in a similar way, and so on, until you travel the shortest path between a_{k-1} and a_k.
  * If you walked over at least one black edge during this process, then the sequence is good. 

<image>

Consider the tree on the picture. If k=3 then the following sequences are good: [1, 4, 7], [5, 5, 3] and [2, 3, 7]. The following sequences are not good: [1, 4, 6], [5, 5, 5], [3, 7, 3].

There are n^k sequences of vertices, count how many of them are good. Since this number can be quite large, print it modulo 10^9+7.

Input

The first line contains two integers n and k (2 ≤ n ≤ 10^5, 2 ≤ k ≤ 100), the size of the tree and the length of the vertex sequence.

Each of the next n - 1 lines contains three integers u_i, v_i and x_i (1 ≤ u_i, v_i ≤ n, x_i ∈ \{0, 1\}), where u_i and v_i denote the endpoints of the corresponding edge and x_i is the color of this edge (0 denotes red edge and 1 denotes black edge).

Output

Print the number of good sequences modulo 10^9 + 7.

Examples

Input


4 4
1 2 1
2 3 1
3 4 1


Output


252

Input


4 6
1 2 0
1 3 0
1 4 0


Output


0

Input


3 5
1 2 1
2 3 0


Output


210

Note

In the first example, all sequences (4^4) of length 4 except the following are good: 

  * [1, 1, 1, 1]
  * [2, 2, 2, 2]
  * [3, 3, 3, 3]
  * [4, 4, 4, 4] 



In the second example, all edges are red, hence there aren't any good sequences.

/**
 * Date: 26 May, 2019
 * Link:
 *
 * @author Prasad-Chaudhari
 * @linkedIn: https://www.linkedin.com/in/prasad-chaudhari-841655a6/
 * @git: https://github.com/Prasad-Chaudhari
 */
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.Stack;

public class newProgram2 {

    public static void main(String[] args) throws IOException {
        // TODO code application logic here
        FastIO in = new FastIO();
        int n = in.ni();
        int k = in.ni();
        long mod = (long) ((1e9) + 7);
        UnionFind uf = new UnionFind(n);
        long ans = 0;
        int from[] = new int[n - 1];
        int to[] = new int[n - 1];
        int x[] = new int[n - 1];
        int count[] = new int[n + 1];
        for (int i = 0; i < n-1; i++) {
            from[i] = in.ni();
            to[i] = in.ni();
            x[i] = in.ni();
            count[from[i]]++;
            count[to[i]]++;
        }
        int adja[][] = new int[n + 1][];
        int xx[][] = new int[n + 1][];

        for (int i = 0; i <= n; i++) {
            adja[i] = new int[count[i]];
            xx[i] = new int[count[i]];
        }

        for (int i = 0; i < n - 1; i++) {
            adja[from[i]][count[from[i]] - 1] = to[i];
            adja[to[i]][count[to[i]] - 1] = from[i];
            xx[from[i]][count[from[i]] - 1] = x[i];
            xx[to[i]][count[to[i]] - 1] = x[i];

            --count[from[i]];
            --count[to[i]];
        }
        Stack<Integer> st = new Stack<>();
        boolean b[] = new boolean[n + 1];
        b[1] = true;
        st.push(1);
        while (!st.isEmpty()) {
            int root = st.pop();
            for (int i = 0; i < adja[root].length; i++) {
                int c = adja[root][i];
                if (!b[c]) {
                    st.push(c);
                    b[c] = true;
                    if (xx[root][i] == 0) {
                        uf.union(root, c);
                    }
                }
            }
        }
        int sizes[] = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            sizes[uf.find(i)] = uf.size[uf.find(i)];
        }
        ans += Expo.a_pow_n_mod_m(n, k, mod);
        for (int i = 1; i <= n; i++) {
            ans -= Expo.a_pow_n_mod_m(sizes[i], k, mod);
            ans += mod;
            ans %= mod;
        }
        
        System.out.println(ans);
    }

    static class Expo {

        static long a_pow_n_mod_m(long a, long n, long m) {
            if (n == 0) {
                return 1;
            }
            if (n == 1) {
                return a;
            }
            long p = a_pow_n_mod_m(a, n / 2, m);
            if (n % 2 == 0) {
                return (p * p) % m;
            } else {
                return ((p * p) % m * a) % m;
            }
        }

        static long a_pow_n(long a, long n) {
            if (n == 0) {
                return 1;
            }
            if (n == 1) {
                return a;
            }
            long p = a_pow_n(a, n / 2);
            if (n % 2 == 0) {
                return (p * p);
            } else {
                return ((p * p) * a);
            }
        }
    }

    static class FastIO {

        private final BufferedReader br;
        private final BufferedWriter bw;
        private String s[];
        private int index;
        private StringBuilder sb;

        public FastIO() throws IOException {
            br = new BufferedReader(new InputStreamReader(System.in));
            bw = new BufferedWriter(new OutputStreamWriter(System.out, "UTF-8"));
            s = br.readLine().split(" ");
            sb = new StringBuilder();
            index = 0;
        }

        public int ni() throws IOException {
            return Integer.parseInt(nextToken());
        }

        public double nd() throws IOException {
            return Double.parseDouble(nextToken());
        }

        public long nl() throws IOException {
            return Long.parseLong(nextToken());
        }

        public String next() throws IOException {
            return nextToken();
        }

        public String nli() throws IOException {
            try {
                return br.readLine();
            } catch (IOException ex) {

            }
            return null;
        }

        public int[] gia(int n) throws IOException {
            int a[] = new int[n];
            for (int i = 0; i < n; i++) {
                a[i] = ni();
            }
            return a;
        }

        public int[] gia(int n, int start, int end) throws IOException {
            validate(n, start, end);
            int a[] = new int[n];
            for (int i = start; i < end; i++) {
                a[i] = ni();
            }
            return a;
        }

        public double[] gda(int n) throws IOException {
            double a[] = new double[n];
            for (int i = 0; i < n; i++) {
                a[i] = nd();
            }
            return a;
        }

        public double[] gda(int n, int start, int end) throws IOException {
            validate(n, start, end);
            double a[] = new double[n];
            for (int i = start; i < end; i++) {
                a[i] = nd();
            }
            return a;
        }

        public long[] gla(int n) throws IOException {
            long a[] = new long[n];
            for (int i = 0; i < n; i++) {
                a[i] = nl();
            }
            return a;
        }

        public long[] gla(int n, int start, int end) throws IOException {
            validate(n, start, end);
            long a[] = new long[n];
            for (int i = start; i < end; i++) {
                a[i] = nl();
            }
            return a;
        }

        public int[][][] gwtree(int n) throws IOException {
            int m = n - 1;
            int adja[][] = new int[n + 1][];
            int weight[][] = new int[n + 1][];
            int from[] = new int[m];
            int to[] = new int[m];
            int count[] = new int[n + 1];
            int cost[] = new int[n + 1];
            for (int i = 0; i < m; i++) {
                from[i] = i + 1;
                to[i] = ni();
                cost[i] = ni();
                count[from[i]]++;
                count[to[i]]++;
            }
            for (int i = 0; i <= n; i++) {
                adja[i] = new int[count[i]];
                weight[i] = new int[count[i]];
            }
            for (int i = 0; i < m; i++) {
                adja[from[i]][count[from[i]] - 1] = to[i];
                adja[to[i]][count[to[i]] - 1] = from[i];
                weight[from[i]][count[from[i]] - 1] = cost[i];
                weight[to[i]][count[to[i]] - 1] = cost[i];
                count[from[i]]--;
                count[to[i]]--;
            }
            return new int[][][]{adja, weight};
        }

        public int[][][] gwg(int n, int m) throws IOException {
            int adja[][] = new int[n + 1][];
            int weight[][] = new int[n + 1][];
            int from[] = new int[m];
            int to[] = new int[m];
            int count[] = new int[n + 1];
            int cost[] = new int[n + 1];
            for (int i = 0; i < m; i++) {
                from[i] = ni();
                to[i] = ni();
                cost[i] = ni();
                count[from[i]]++;
                count[to[i]]++;
            }
            for (int i = 0; i <= n; i++) {
                adja[i] = new int[count[i]];
                weight[i] = new int[count[i]];
            }
            for (int i = 0; i < m; i++) {
                adja[from[i]][count[from[i]] - 1] = to[i];
                adja[to[i]][count[to[i]] - 1] = from[i];
                weight[from[i]][count[from[i]] - 1] = cost[i];
                weight[to[i]][count[to[i]] - 1] = cost[i];
                count[from[i]]--;
                count[to[i]]--;
            }
            return new int[][][]{adja, weight};
        }

        public int[][] gtree(int n) throws IOException {
            int adja[][] = new int[n + 1][];
            int from[] = new int[n - 1];
            int to[] = new int[n - 1];
            int count[] = new int[n + 1];
            for (int i = 0; i < n - 1; i++) {
                from[i] = i + 1;
                to[i] = ni();
                count[from[i]]++;
                count[to[i]]++;
            }
            for (int i = 0; i <= n; i++) {
                adja[i] = new int[count[i]];
            }
            for (int i = 0; i < n - 1; i++) {
                adja[from[i]][--count[from[i]]] = to[i];
                adja[to[i]][--count[to[i]]] = from[i];
            }
            return adja;
        }

        public int[][] gg(int n, int m) throws IOException {
            int adja[][] = new int[n + 1][];
            int from[] = new int[m];
            int to[] = new int[m];
            int count[] = new int[n + 1];
            for (int i = 0; i < m; i++) {
                from[i] = ni();
                to[i] = ni();
                count[from[i]]++;
                count[to[i]]++;
            }
            for (int i = 0; i <= n; i++) {
                adja[i] = new int[count[i]];
            }
            for (int i = 0; i < m; i++) {
                adja[from[i]][--count[from[i]]] = to[i];
                adja[to[i]][--count[to[i]]] = from[i];
            }
            return adja;
        }

        public void print(String s) throws IOException {
            bw.write(s);
        }

        public void println(String s) throws IOException {
            bw.write(s);
            bw.newLine();
        }

        private String nextToken() throws IndexOutOfBoundsException, IOException {
            if (index == s.length) {
                s = br.readLine().split(" ");
                index = 0;
            }
            return s[index++];
        }

        private void validate(int n, int start, int end) {
            if (start < 0 || end >= n) {
                throw new IllegalArgumentException();
            }
        }
    }

    static class Data implements Comparable<Data> {

        int a, b;

        public Data(int a, int b) {
            this.a = a;
            this.b = b;
        }

        @Override
        public int compareTo(Data o) {
            if (a == o.a) {
                return Integer.compare(b, o.b);
            }
            return Integer.compare(a, o.a);
        }

        public static void sort(int a[]) {
            Data d[] = new Data[a.length];
            for (int i = 0; i < a.length; i++) {
                d[i] = new Data(a[i], 0);
            }
            Arrays.sort(d);
            for (int i = 0; i < a.length; i++) {
                a[i] = d[i].a;
            }
        }
    }

    static class UnionFind {

        private int noOfComponents, n;
        private int component[], size[];
        private ArrayList<LinkedList<Integer>> members;

        public UnionFind(int p) {
            n = p;
            noOfComponents = n;
            component = new int[n + 1];
            size = new int[n + 1];
            members = new ArrayList<>();
            for (int i = 0; i <= n; i++) {
                component[i] = i;
                size[i] = 1;
                members.add(new LinkedList<Integer>());
                members.get(i).add(i);
            }
        }

        public int find(int k) {
            return component[k];
        }

        public void union(int a, int b) {
            a = find(a);
            b = find(b);
            if (a == b) {
                return;
            }
            if (size[a] > size[b]) {
                a = a ^ b;
                b = a ^ b;
                a = a ^ b;
            }
            LinkedList<Integer> membersofa = members.get(a);
            LinkedList<Integer> membersofb = members.get(b);
            for (int i = 0; i < size[a]; i++) {
                int member = membersofa.removeFirst();
                component[member] = component[b];
                membersofb.add(member);
            }
            size[b] = size[b] + size[a];
            noOfComponents--;
        }

        public int noOfComponents() {
            return noOfComponents;
        }
    }

}
