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#include <bits/stdc++.h>
using namespace std;
using vi=vector<int>;
using ll=long long;
#define pb push_back
#define fst first
#define snd second
using vll=vector<ll>;
using Pii=pair<int,int>;
using Pll=pair<ll,ll>;
using vpii=vector<Pii>;
#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
#define sim template <class c
#define mor > muu & operator<<(
#define ris return *this
#define R22(r) sim> typename enable_if<1 r sizeof(dud<c>(0)),muu&>::type operator<<(c g) {
sim> struct rge {c b, e;};
sim> rge<c> range(c i, c j) {return rge<c>{i, j};}
sim> auto dud(c*r)->decltype(cerr << *r);
sim> char dud(...);
struct muu {
	#ifdef LOCAL
	stringstream a;
	~muu() {cerr << a.str() << endl;}
	R22(<) a << boolalpha << g; ris;}
	R22(==) ris << range(begin(g), end(g));}
	sim mor rge<c> u) {
		a << "[";
		for (c i = u.b; i != u.e; ++i)
			*this << ", " + 2 * (i == u.b) << *i;
		ris << "]";
	}
	sim, class m mor pair<m,c> r) {ris << "(" << r.first << ", " << r.second << ")";}
	#else
	sim mor const c &){ris;}
	#endif
	muu & operator()(){ris;}
};
#define imie(r) "[" #r ": " << (r) << "] "
#define debug (muu() << __FUNCTION__ << "#" << __LINE__ << ": " )
const int maxn = 1e5;
vector<Pll> E[maxn];
bool wyjebane[maxn];
int w_poddrzewie[maxn];
int w_dzieciach[maxn];
bool visited[maxn];

void dfs(int x, vector<int>& wierzcholki)
{
	visited[x] = true;
	w_poddrzewie[x] = 1;
	w_dzieciach[x] = 0;
	wierzcholki.push_back(x);
	for(Pll p : E[x])
	{
		int y = p.first;
		if(!wyjebane[y] && !visited[y])
		{
			dfs(y, wierzcholki);
			w_poddrzewie[x] += w_poddrzewie[y];
			w_dzieciach[x] = max(w_dzieciach[x], w_poddrzewie[y]);
		}
	}
}

pair<int, vi> znajdz_centroid(int x)
{
	vi W;
	dfs(x, W);
	for(int v : W)
		visited[v] = false;
	int total_size = w_poddrzewie[x];
	int sz = W.size();
	for(int v : W)
	{
		if(w_dzieciach[v] <= sz/2 && total_size - w_poddrzewie[v] <= sz/2)
			return {v, W};
	}
	assert(false);
	//return -1;
}
ll limit;
void dfs2(int x, ll acc, vll& paths)
{
	paths.push_back(acc);
	assert(acc != 0);
	visited[x] = true;
	for(Pll p : E[x])
		if(!wyjebane[p.first] && !visited[p.first])
			dfs2(p.first, acc + p.second, paths);
}
int jebaj_sciezki_single(vector<ll> A, vector<ll> B)
{
	int res = 0;
	sort(A.begin(), A.end());
	sort(B.begin(), B.end());
	int idx = (int)B.size() - 1;
	for(ll x : A)
	{
		while(idx >= 0 && x + B[idx] > limit)
			--idx;
			
		res += idx + 1;
	}
	return res;
}
int jebaj_sciezki(vector<vll> sc)
{
	if((int)sc.size() < 2) return 0;
	int sz = sc.size();
	vector<vll> A, B;
	vll a, b;
	for(int i = 0; i < sz/2; ++i)
	{
		A.push_back(sc[i]);
		for(ll v : sc[i])
			a.push_back(v);
	}
	for(int i = sz/2; i < sz; ++i)
	{
		B.push_back(sc[i]);
		for(ll v : sc[i])
			b.push_back(v);
	}
	return jebaj_sciezki(A) + jebaj_sciezki(B) + jebaj_sciezki_single(a, b);
}
int jebaj(int x)
{
	int res = 0;
	auto P = znajdz_centroid(x);
	vi wierzcholki = P.second;
	x = P.first;
	wyjebane[x] = true;
	vector<vll> sciezki = {{0}};
	for(Pll p : E[x])
		if(!wyjebane[p.first])
		{
			vll pat;
			dfs2(p.first, p.second, pat);
			res += jebaj(p.first);
			sciezki.push_back(pat);
		}
	debug() << imie(x);
	return res + jebaj_sciezki(sciezki);
}
int n, k;
const int D = 16;
const int maska = (1 << D) - 1;
int main()
{
	scanf("%d%d", &n, &k);
	int licz[4] = {0,0,0,0};
	for(int i = 1; i < n; ++i)
	{
		int a, b, p;
		scanf("%d%d%d", &a, &b, &p);
		--a; --b; --p;
		ll wyk = 1ll << (D * p);
		debug() << imie(wyk);
		E[a].push_back({b, wyk});
		E[b].push_back({a, wyk});
		licz[p]++;
	}
	ll b = -1;
	ll e = n * (1ll << D * 3);
	while(e - b > 1)
	{
		ll d = (b + e) / 2;
		limit = d;
		debug() << "KURWA";
		for(int i = 0; i < n; ++i)
			wyjebane[i] = visited[i] = false;
		if(jebaj(0) < k)
			b = d;
		else
			e = d;
		//~ for(int i = 0; i < n; ++i)
			//~ debug() << imie(wyjebane[i]);
	}
	ll mn = n;
	ll res = 0;
	while(e > 0)
	{
		res += mn * (e & maska);
		e >>= D;
		mn = n * mn;
	}
	const ll mod = 1e9 + 7;
	printf("%lld\n", res % mod);
	
}