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.
	/*	/ ﾌﾌ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ム
		/ )\⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀  Y
		(⠀⠀| ( ͡° ͜ʖ ͡°）⠀⌒(⠀ ノ
		(⠀ ﾉ⌒ Y ⌒ヽ-く __／
		| _⠀｡ノ| ノ｡ |/
		(⠀ー '_人`ー ﾉ
		⠀|\ ￣ _人'彡ﾉ
		⠀ )\⠀⠀ ｡⠀⠀ /
		⠀⠀(\⠀ #⠀ /
		⠀/⠀⠀⠀/ὣ====================D-
		/⠀⠀⠀/⠀ \ \⠀⠀\
		( (⠀)⠀⠀⠀⠀ ) ).⠀)
		(⠀⠀)⠀⠀⠀⠀⠀( | /
		|⠀ /⠀⠀⠀⠀⠀⠀ | /
		[_] ⠀⠀⠀⠀⠀[___]                     */
	// Main Code at the Bottom
	import java.util.*;
	import java.lang.*;
	import java.io.*;
	import java.math.BigInteger; 
	public class Main {
		//Fast IO class
	    static class FastReader {
	        BufferedReader br; 
	        StringTokenizer st; 
	        public FastReader() {
	        	boolean env=System.getProperty("ONLINE_JUDGE") != null;
	        	if(!env) {
	        		try {
						br=new BufferedReader(new FileReader("src\\input.txt"));
					} catch (FileNotFoundException e) {
						e.printStackTrace();
					}
	        	}
	        	else br = new BufferedReader(new InputStreamReader(System.in)); 
	        } 
	        String next() {
	            while (st == null || !st.hasMoreElements()) {
	                try {
	                    st = new StringTokenizer(br.readLine()); 
	                } 
	                catch (IOException  e) {
	                    e.printStackTrace(); 
	                } 
	            } 
	            return st.nextToken(); 
	        } 
	        int nextInt() {
	            return Integer.parseInt(next()); 
	        } 
	        long nextLong() {
	            return Long.parseLong(next()); 
	        } 
	        double nextDouble() {
	            return Double.parseDouble(next()); 
	        } 
	        String nextLine() {
	            String str = ""; 
	            try {
	                str = br.readLine(); 
	            } 
	            catch (IOException e) {
	                e.printStackTrace(); 
	            } 
	            return str; 
	        } 
	    }     
	    static long MOD=1000000000+7;
	    //Euclidean Algorithm
	    static long gcd(long A,long B){
	    	return (B==0)?A:gcd(B,A%B);
	    }
	    //Modular Exponentiation
	    static long fastExpo(long x,long n){
	        if(n==0) return 1;
	        if((n&1)==0) return fastExpo((x*x)%MOD,n/2)%MOD;
	        return ((x%MOD)*fastExpo((x*x)%MOD,(n-1)/2))%MOD;
	    }
	    //Modular Inverse
	    static long inverse(long x) {
	    	return fastExpo(x,MOD-2);
	    }
	    //Prime Number Algorithm
	    static boolean isPrime(long n){
	        if(n<=1) return false;
	        if(n<=3) return true;
	        if(n%2==0 || n%3==0) return false;
	        for(int i=5;i*i<=n;i+=6) if(n%i==0 || n%(i+2)==0) return false;
	        return true;
	    }
	    //Reverse an array
	    static void reverse(int arr[],int l,int r){
	    	while(l<r) {
	    		int tmp=arr[l];
	    		arr[l++]=arr[r];
	    		arr[r--]=tmp;
	    	}
	    }
	    //Print array
	    static void print1d(int arr[]) {
	    	out.println(Arrays.toString(arr));
	    }
	    static void print2d(long arr[][]) {
	    	for(long a[]: arr) out.println(Arrays.toString(a));
	    }
	    // Pair
	    static class pair{
	    	int x,y;
	    	pair(int a,int b){
	    		this.x=a;
	    		this.y=b;
	    	}
	    	public boolean equals(Object obj) {
	    		if(obj == null || obj.getClass()!= this.getClass()) return false;
	            pair p = (pair) obj;
	            return (this.x==p.x && this.y==p.y);
	        }
	    	public int hashCode() {
	            return Objects.hash(x,y);
	        }
	    }
	    static FastReader sc=new FastReader();
	    static PrintWriter out=new PrintWriter(System.out);  
	    //Main function(The main code starts from here)
	    static int parent[];
	    static void init(int n) {
	    	parent=new int[n];
	    	for(int i=0;i<n;i++) parent[i]=-1;
	    }
	    static int find(int x) {
	    	if(parent[x]<0) return x;
	    	return parent[x]=find(parent[x]);
	    }
	    static void union(int a,int b) {
	    	a=find(a);b=find(b);
	    	if(a!=b) {
	    		parent[b]+=parent[a];
	    		parent[a]=b;
	    	}
	    }
	    public static void main (String[] args) throws java.lang.Exception {
	    	int test;
	    	test=1;
	    	//test=sc.nextInt();
	    	while(test-->0){
	    		int n=sc.nextInt(),k=sc.nextInt();
	    		init(n);
	    		for(int i=0;i<n-1;i++) {
	    			int src=sc.nextInt()-1,dest=sc.nextInt()-1,color=sc.nextInt();
	    			if(color==1) continue;
	    			union(src,dest);
	    		}
	    		long ans=fastExpo(n,k);
	    		for(int i=0;i<n;i++) {
	    			if(parent[i]>=0) continue;
	    			int val=-parent[i];
	    			ans=(ans%MOD-fastExpo(val,k)%MOD+MOD)%MOD;
	    		}
	    		out.println(ans);
	    	}
	    	
	        out.flush();
	        out.close();
	    }
	}