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.*;
import java.util.*;

public class C_Edgy_Trees{
    static int MOD = (int)1e9+7;
    @SuppressWarnings("unchecked")
    public static void main(String[] args) throws Exception{
        int[] nk = in.readA();
        int n = nk[0], k = nk[1];
        int N = n;
        List<Integer>[] g = new List[n];
        for(int i = 0; i < n; i++)
            g[i] = new ArrayList<>();
        while(N-- > 1){
            int[] uvc = in.readA();
            int u = uvc[0]-1, v = uvc[1]-1, c = uvc[2];

            if(c == 0){
                g[u].add(v);
                g[v].add(u);
            }
        }
        // count components
        boolean[] visited = new boolean[n];
        
        long ans = pow(n,k), sub = 0;

        for(int i = 0; i < n; i++){
            if(!visited[i]){
                int p = dfs(i, visited, g);
                sub = (sub + pow(p,k));
            }
        }
        sub%=MOD;
        System.out.println((ans-sub+MOD)%MOD);
    }

    public static int dfs(int u, boolean[] visited, List<Integer>[] g){
        if(visited[u])
            return 0;
        visited[u] = true;
        int count = 1;
        for(int v : g[u]){
            count += dfs(v, visited, g);
        }
        return count;
    }

    public static int pow(int x, int n){
        if(x == 0)  return 0;
        if(n == 0)  return 1;
        int half = pow(x, n/2);
        long ans = (half*half)%MOD;
        if(n%2 == 1)
            ans = (ans*x)%MOD;
        return (int)ans;
    }

    static Inputer in;
    static {
        in = new Inputer();
    }

    static class Inputer{
        BufferedReader br;
        Inputer(){
            try{
                br = new BufferedReader(new InputStreamReader(System.in));
            }
            catch(Exception e){}
        }
        public int readInt() throws Exception{
            return Integer.parseInt(readLine());
        }
        public long readLong() throws Exception{
            return Long.parseLong(readLine());
        }
        public int[] readA(String delim) throws Exception{
            String[] s = readLine().split(delim);
            int[] A = new int[s.length];
            for(int i = 0; i < s.length; i++)
                A[i] = Integer.parseInt(s[i]);
            return A;
        }
        public int[] readA() throws Exception{
            String[] s = readLine().split("\\s+");
            int[] A = new int[s.length];
            for(int i = 0; i < s.length; i++)
                A[i] = Integer.parseInt(s[i]);
            return A;
        }
        public long[] readLA() throws Exception{
            String[] s = readLine().split("\\s+");
            long[] A = new long[s.length];
            for(int i = 0; i < s.length; i++)
                A[i] = Long.parseLong(s[i]);
            return A;
        }
        public String readLine() throws Exception{
            return br.readLine();
        }
        public int[] copyA(int[] A){
            int[] B = new int[A.length];
            for(int i= 0 ; i < A.length; i++)
                B[i] = A[i];
            return B;
        }
    }
    static void shuffle(int[] A){
        int n = A.length;
        Random rand = new Random();
        for(int t = 0; t < A.length; t++){
            int i1 = rand.nextInt(n);
            int i2 = rand.nextInt(n);
            int tmp = A[i1];
            A[i1] = A[i2];
            A[i2] = tmp;
        }
    }
    static class Pair{
        int first, second;
        Pair(){
        }
        Pair(int a, int b){
            first = a;
            second = b;
        }
        @Override
        public String toString() {
            return "{"+first+","+second+"}";
        }
    }
}