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.
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.FileNotFoundException;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import java.io.Writer;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in Actual solution is at the top
 */
public class Main {
  public static void main(String[] args) {
    InputStream inputStream = System.in;
    OutputStream outputStream = System.out;
    InputReader in = new InputReader(inputStream);
    OutputWriter out = new OutputWriter(outputStream);
    TaskC solver = new TaskC();
    solver.solve(1, in, out);
    out.close();
  }

  static class TaskC extends ChelperSolution {
    LongMod MOD = new LongMod(1000000007L);

    public void solve(int testNumber, InputReader in, OutputWriter out) {
      super.solve(testNumber, in, out);
    }

    public void solve(int testNumber) {
      int n = in.nextInt();
      int k = in.nextInt();

      List<List<Integer>> edges = new ArrayList<>();

      for (int i = 0; i < n; i++) {
        edges.add(new ArrayList<>());
      }

      for (int i = 0; i < n - 1; i++) {
        int v1 = in.nextInt() - 1;
        int v2 = in.nextInt() - 1;
        int color = in.nextInt();

        if (color == 1) {
          continue;
        }

        edges.get(v1).add(v2);
        edges.get(v2).add(v1);
      }

      boolean[] visited = new boolean[n];

      long totalCount = MOD.pow(n, k);
      long badCount = 0;

      for (int i = 0; i < n; i++) {
        int componentSize = dfs(i, edges, visited);

        badCount = MOD.sum(badCount, MOD.pow(componentSize, k));
      }

      long goodCount = MOD.sub(totalCount, badCount);

      out.println(goodCount);
    }

    private int dfs(int v, List<List<Integer>> edges, boolean[] visited) {
      if (visited[v]) {
        return 0;
      }

      visited[v] = true;
      int res = 1;

      for (int u : edges.get(v)) {
        res += dfs(u, edges, visited);
      }

      return res;
    }

  }

  static abstract class ChelperSolution implements ChelperCallable {
    public static final String LOCAL_FILE = "chelper.properties";
    public static final String SAVE_RESULT_FILE = "last_test_output.txt";
    protected final boolean local = new File(LOCAL_FILE).exists();
    protected boolean firstTest = true;
    protected InputReader in;
    protected OutputWriter out;
    protected OutputWriter debug;
    protected OutputWriter fileOut;
    protected boolean saveTestResult = true;
    protected boolean gcj = false;

    protected void init() {
      if (local) {
        debug = new OutputWriter(System.err);
        if (saveTestResult) {
          fileOut = OutputWriter.toFile(SAVE_RESULT_FILE);
        }
      } else {
        debug = new OutputWriter(new NullOutputStream());
      }
    }

    public void solve(int testNumber, InputReader in, OutputWriter out) {
      if (firstTest) {
        init();
        precalc();
        firstTest = false;
      }

      this.in = in;
      if (local && saveTestResult) {
        this.out = new SplittingOutputWriter(out, fileOut);
      } else {
        this.out = out;
      }

      preSolve(testNumber);
      solve(testNumber);
      postSolve(testNumber);
    }

    protected void precalc() {

    }

    protected void preSolve(int testNumber) {
      if (gcj) {
        out.printf("Case #%d: ", testNumber);
      }
    }

    public abstract void solve(int testNumber);

    protected void postSolve(int testNumber) {
      out.flush();
      debug.flush();
    }

  }

  static class OutputWriter extends PrintWriter {
    public static OutputWriter toFile(String fileName) {
      try {
        return new OutputWriter(fileName);
      } catch (FileNotFoundException e) {
        throw new RuntimeException(e);
      }
    }

    public void close() {
      super.close();
    }

    public OutputWriter(String fileName) throws FileNotFoundException {
      super(fileName);
    }

    public OutputWriter(OutputStream outputStream) {
      super(outputStream, true);
    }

    public OutputWriter(Writer writer) {
      super(writer, true);
    }

  }

  static class NullOutputStream extends OutputStream {
    public void write(int b) throws IOException {
      // nothing
    }

  }

  static class LongMod {
    public final long mod;

    public LongMod(long mod) {
      if (mod <= 0) {
        throw new IllegalArgumentException();
      }
      this.mod = mod;
    }

    public long mod(long val) {
      return val % mod;
    }

    public long sum(long a, long b) {
      return (a + b) % mod;
    }

    public long sub(long a, long b) {
      return mod(mod(a - b) + mod);
    }

    public long prod(long a, long b) {
      return (a * b) % mod;
    }

    public long pow(long a, long b) {
      if (b < 0) {
        throw new IllegalArgumentException();
      }

      if (b == 0) {
        return 1 % mod;
      }

      if (b == 1) {
        return a % mod;
      }

      if (b % 2 == 0) {
        long c = pow(a, b / 2);
        return prod(c, c);
      } else {
        return prod(a, pow(a, b - 1));
      }
    }

  }

  static class SplittingOutputWriter extends OutputWriter {
    private final OutputWriter[] outputWriters;

    public SplittingOutputWriter(OutputWriter... outputWriters) {
      super(new OutputStream() {

        public void write(int b) throws IOException {
          for (OutputWriter outputWriter : outputWriters) {
            outputWriter.write(b);
          }
        }
      });

      this.outputWriters = outputWriters;
    }

    public void flush() {
      for (OutputWriter outputWriter : outputWriters) {
        outputWriter.flush();
      }
    }

    public void close() {
      for (OutputWriter outputWriter : outputWriters) {
        outputWriter.close();
      }
    }

  }

  static interface ChelperCallable {
  }

  static class InputReader {
    private BufferedReader br;
    private StringTokenizer in;

    public InputReader(String fileName) {
      try {
        br = new BufferedReader(new FileReader(fileName));
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }

    public InputReader(InputStream inputStream) {
      br = new BufferedReader(new InputStreamReader(inputStream));
    }

    private boolean hasMoreTokens() {
      while (in == null || !in.hasMoreTokens()) {
        String s = nextLine();
        if (s == null) {
          return false;
        }
        in = new StringTokenizer(s);
      }
      return true;
    }

    public String nextString() {
      return hasMoreTokens() ? in.nextToken() : null;
    }

    public String nextLine() {
      try {
        in = null;
        return br.readLine();
      } catch (Exception e) {
        e.printStackTrace();
        return null;
      }
    }

    public int nextInt() {
      return Integer.parseInt(nextString());
    }

  }
}

