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#include <bits/stdc++.h>
using namespace std;
#define debug(x) cerr << #x << " " << x << endl;

// #define int long long // uważaj

const long long N = 3e4 + 7, mod = 1e9 + 7;
int ograniczenia[N];
int akt[N];
vector<pair<int, int> > G[N];
int n, k;
int ile_ustalonych;
int id_ustalonych;

int dfs(int v, int oj) {
    int ret = 0;
    if(ile_ustalonych == 0 and oj != 0) ret ++;
    for(auto x : G[v]) {
        if(x.first == oj) continue;
        if(ograniczenia[x.second] == akt[x.second]) continue;
        akt[x.second] ++;
        if(akt[x.second] == ograniczenia[x.second] and x.second >= id_ustalonych) ile_ustalonych--;
        ret += dfs(x.first, v);
        if(akt[x.second] == ograniczenia[x.second] and x.second >= id_ustalonych) ile_ustalonych++;
        akt[x.second] --;
    }
    return ret;
}

int test() {
    int ret = 0;
    for(int i = 1; i <= n; i++) {
        ret += dfs(i, 0);
        // int zm = dfs(i, 0);
    }
    return ret / 2;
}

void solve() {
    cin >> n >> k;
    for(int i = 1; i < n; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        G[a].push_back({b, c});
        G[b].push_back({a, c});
        ograniczenia[c] ++;
    }

    id_ustalonych = 1e5;

    for(int i = n; i > 0; i--) {
        while(ograniczenia[i] > 0) {
            ograniczenia[i] --;
            int zm = test();
            if(zm < k) {
                ograniczenia[i] ++;
                ile_ustalonych ++;
                k -= zm;
                break;
            }
        }
        id_ustalonych = i;
    }

    long long ans = 0;
    long long pot = 1;
    for(int i = 1; i <= n; i++) {
        pot *= n;
        pot %= mod;
        ans += ograniczenia[i] * pot;
        ans %= mod;
    }

    cout << ans << endl;
}

int32_t main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);

	int test = 1;

	while(test--){
		solve();
	}

	return 0;
}