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.
//package Practice_Problems;
import java.util.*;
import java.io.*;
public class EdgyTrees
{
	static ArrayList<Integer> adj[] = new ArrayList[(int) 1e5 + 1];
	static boolean vis[]=new boolean[adj.length];
	static final int mod=(int)1e9+7;
	static final int inf=(int)1e9;
	static final long INF=(long)1e18;
	static int cnt=0;
	public static void main(String[] args) throws IOException
	{
		FastScanner fs=new FastScanner();
		PrintWriter out = new PrintWriter(System.out);
		int nodes=fs.nextInt();
		int k=fs.nextInt();
		for(int i=1;i<=nodes;i++)adj[i]=new ArrayList<Integer>();
		for(int i=1;i<=nodes-1;i++)
		{
			int a=fs.nextInt();int b=fs.nextInt();int col=fs.nextInt();
			if(col==0)
			{adj[a].add(b);adj[b].add(a);}
		}
		long ans=modpow(nodes,k);
		long sub=0;
		for(int i=1;i<=nodes;i++)
		{
			if(!vis[i])
			{
				dfs(i);
				sub=sub+modpow(cnt,k);
				cnt=0;
			}
		}
		//System.out.println(sub+" "+ans);
		sub%=mod;
		ans=(ans-sub+mod)%mod;
		out.println(ans);
		out.close();
	}
	public static long modpow(long x,long n)
	{
		long res=1;
		while(n>0)
		{
			//System.out.println(x+" "+n+" "+res);
			if(n%2!=0)
			{
				res=((res%mod)*(x%mod))%mod;n--;
			}
			else
				{x=((x%mod)*(x%mod))%mod;n/=2;}
		}
		return res;
	}
	public static void dfs(int node)
	{
		vis[node]=true;
		cnt++;
		for(int child:adj[node])
		{
			if(!vis[child])dfs(child);
		}
	}
	//returns the index of the smallest element in the array that is greater than or equal to
	//the given element.
	public static int lower_bound(int arr[],int key)
	{
		int index=inf,num=0;
		int left=0,right=arr.length-1;
		while(left<=right)
		{
			int mid=left+(right-left)/2;
			if(arr[mid]>=key) {index=mid;num=arr[mid];right=mid-1;}
			else 
				left=mid+1;
		}
		return index==inf ? arr.length:index;
	}
	//returns the index of the smallest element in the array that is less than or equal to
    //the given element.
	public static int upper_bound(int arr[],int key)
	{
		int index=inf,num=0;
		int left=0,right=arr.length-1;
		while(left<=right)
		{
			int mid=left+(right-left)/2;
			if(arr[mid]<=key) {index=mid;num=arr[mid];left=mid+1;}
			else 
				right=mid-1;
		}
		return index==inf ? arr.length:index;
	}
}
class FastScanner 
{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer("");
		public String next() 
		{
			while (!st.hasMoreTokens())
				try {
					st=new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			return st.nextToken();
			
		}
		public String nextLine() throws IOException
		{
		    return br.readLine();
		}
		int[] sort(int arr[])
		{
			ArrayList<Integer> list = new ArrayList<Integer>();
			for(int i:arr)list.add(i);
			Collections.sort(list);
			for(int i=0;i<arr.length;i++)
			{
				arr[i]=list.get(i);
			}
			return arr;
		}
		char[] charsort(char arr[])
	        {
	    	ArrayList<Character> list = new ArrayList<>();
	    	for(char c:arr)list.add(c);
	    	Collections.sort(list);
	    	for(int i=0;i<list.size();i++)
	    	{
	    		arr[i]=list.get(i);
	    	}
	    	return arr;
	        }
		long[] longsort(long arr[])
		{
			ArrayList<Long> list = new ArrayList<Long>();
			for(long i:arr)list.add(i);
			Collections.sort(list);
			for(int i=0;i<arr.length;i++)
			{
				arr[i]=list.get(i);
			}
			return arr;
		}
		public int nextInt() 
		{
			return Integer.parseInt(next());
		}
		public int[] readArray(int n)
		{
			int[] arr=new int[n];
			for (int i=0; i<n; i++) arr[i]=nextInt();
			return arr;
		}	
		public long nextLong()
		{
			return Long.parseLong(next());
		}
		public long[] longreadArray(int n) 
		{
			long[] a=new long[n];
			for (int i=0; i<n; i++) a[i]=nextLong();
			return a;
		}
}
