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#include <bits/stdc++.h>


using namespace std;


const int MOD = 1000 * 1000 * 1000 + 7;
const long long HMOD = 1000000LL * 1000000LL * 1000000LL + 3;

struct edge {
    int u, v, p;
};

long long randomHash() {
    long long res = 0;

    res ^= rand();
    res <<= 32;
    res ^= rand();

    return res % HMOD;
}

void addHash(long long &x, long long val) {
    x += val;
    if (x >= HMOD) {
        x -= HMOD;
    }
}

void subHash(long long &x, long long val) {
    x -= val;
    if (x < 0) {
        x += HMOD;
    }
}

struct Centroid {
    const int MAXLG = 20;

    vector <vector<int>> edges;
    
    vector <bool> taken;
    vector <int> size;

    vector <int> jump; // output: parent
    vector <int> depth; // output: layer
    vector <vector<int>> dist, from, parent; // output: dist from ancestor at given depth, and first on path
    
    Centroid(int n):
        edges(n), taken(n, false), size(n), jump(n), depth(n),
        dist(MAXLG, vector <int> (n)), from(MAXLG, vector <int> (n)), parent(MAXLG, vector <int> (n, -1)) {}

    void addEdge(int u, int v) {
        edges[u].push_back(v);
        edges[v].push_back(u);
    }

    void updateSize(int u) {
        taken[u] = size[u] = 1;
        
        for (int v : edges[u]) if (!taken[v]) {
            updateSize(v);
            size[u] += size[v];
        }
        
        taken[u] = 0;
    }

    pair <int,int> centroid(int u, int n) {
        taken[u] = 1;
        pair <int,int> r = {n - size[u], u};
        
        for (int v : edges[u]) if (!taken[v]) r.first = max(r.first, size[v]);
        for (int v : edges[u]) if (!taken[v]) r = min(r, centroid(v, n));
        
        taken[u] = 0;
        return r;
    }

    void fillDist(int u, int d, int par, int layer) {
        taken[u] = 1;
        dist[layer][u] = d;
        from[layer][u] = par;
        
        if (par == -1) {
            par = u;
        }
        
        for (int v : edges[u]) if (!taken[v]) {
            parent[layer][v] = u;
            fillDist(v, d + 1, par, layer);
        }

        taken[u] = 0;
    }

    void decompose(int u, int p, int layer) {
        updateSize(u);
        int n = size[u];
        u = centroid(u, n).second;

        jump[u] = p;
        depth[u] = layer;
        
        fillDist(u, 0, -1, layer);
        taken[u] = 1;
        
        for (int v : edges[u]) if (!taken[v]) decompose(v, u, layer+1);
    }

    void decompose() { decompose(0, 0, 0); }
};

vector <int> ubs;

void dfs(int u, long long h, vector <vector<pair<int,int>>> &g, function <long long(int)> &getHash, vector <long long> &seen) {
    seen.push_back(h);

    for (auto &e : g[u]) {
        int v = e.first;
        if (!ubs[e.second]) continue;

        ubs[e.second]--;

        long long hHere = getHash(e.second);
        addHash(hHere, h);

        dfs(v, hHere, g, getHash, seen);

        ubs[e.second]++;
    }
}

unordered_map <long long,int> cnt;

int countRootPaths(int u, vector <vector<pair<int,int>>> &g, int i, vector <long long> &pHash, long long targetHash) {
    function <long long(int)> getHash = [&](int p) {
        return p >= i ? pHash[p] : 0;
    };

    int ans = 0;

    cnt.clear();
    cnt[0] = 1;

    for (auto &e : g[u]) {
        int v = e.first;
        if (!ubs[e.second]) continue;

        ubs[e.second]--;

        long long h = getHash(e.second);

        vector <long long> seen;
        dfs(v, h, g, getHash, seen);

        for (long long &hHere : seen) {
            long long target = targetHash;
            subHash(target, hHere);

            auto f = cnt.find(target);
            if (f != cnt.end()) {
                ans += f->second;
            }
        }

        for (long long &hHere : seen) {
            cnt[hHere]++;
        }

        ubs[e.second]++;
    }

    return ans;
}

int solve(int n, int k, vector <edge> &edges) {
    vector <vector<pair<int,int>>> edgesPerCost(n);
    map <pair<int,int>,int> costForEdge;

    Centroid centroid(n);

    for (auto &e : edges) {
        edgesPerCost[e.p].push_back({e.u, e.v});

        costForEdge[{e.u, e.v}] = e.p;
        costForEdge[{e.v, e.u}] = e.p;

        centroid.addEdge(e.u, e.v);
    }

    centroid.decompose();

    vector <vector<int>> forRoot(n);
    for (int v = 0; v < n; v++) {
        int anc = v;

        for (int level = centroid.depth[v]; level >= 0; level--) {
            forRoot[anc].push_back(v);
            anc = centroid.jump[anc];
        }
    }

    vector <vector<vector<pair<int,int>>>> tree(n);
    vector <int> treeRootId(n);

    vector <vector<int>> rootsWithCost(n);

    for (int root = 0; root < n; root++) {
        auto verts = forRoot[root];
        sort(verts.begin(), verts.end());

        int m = verts.size();
        tree[root].resize(m);

        auto mapDown = [&](int u) {
            return lower_bound(verts.begin(), verts.end(), u) - verts.begin();
        };

        for (int v : verts) if (v != root) {
            int par = centroid.parent[centroid.depth[root]][v];
            int cost = costForEdge[{par, v}];

            tree[root][mapDown(par)].push_back({mapDown(v), cost});
            rootsWithCost[cost].push_back(root);
        }

        treeRootId[root] = mapDown(root);
    }

    vector <int> power(n, n);
    for (int i = 1; i < n; i++) {
        power[i] = ((long long) power[i - 1] * n) % MOD;
    }

    vector <long long> pHash(n);
    for (auto &h : pHash) {
        h = randomHash();
    }

    int ans = 0;
    long long expHash = 0;

    vector <int> rootsAlive;
    for (int root = 0; root < n; root++) if (forRoot[root].size() > 1) {
        rootsAlive.push_back(root);
    }

    ubs.resize(n, n);

    for (int i = n - 1; i >= 0; i--) if (!edgesPerCost[i].empty()) {
        vector <int> inRoot(n, 0);
        for (int root : rootsWithCost[i]) {
            inRoot[root]++;
        }

        for (int m = 0; m < edgesPerCost[i].size(); m++) {
            int cntHere = 0;
            vector <int> rootsAliveHere;

            for (int root : rootsAlive) if (inRoot[root] >= m) {
                int res = countRootPaths(treeRootId[root], tree[root], i, pHash, expHash);

                if (res > 0) {
                    cntHere += res;
                    rootsAliveHere.push_back(root);
                }
            }

            if (cntHere >= k) {
                rootsAlive = rootsAliveHere;
                ubs[i] = m;

                break;
            } else {
                k -= cntHere;
            }

            ans = (ans + power[i]) % MOD;
            addHash(expHash, pHash[i]);
        }
    }

    return ans;
}

int main() {
    ios_base::sync_with_stdio(false);

    int n, k;
    cin >> n >> k;

    vector <edge> edges(n - 1);

    for (auto &e : edges) {
        cin >> e.u >> e.v >> e.p; e.u--; e.v--; e.p--;
    }

    cout << solve(n, k, edges);

    return 0;
}