#include <bits/stdc++.h>
#define all(vec) vec.begin(), vec.end()
#define eb emplace_back
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
constexpr ll INF = (1LL << 30) - 1LL;
constexpr ll LINF = (1LL << 60) - 1LL;
constexpr ll MOD = 1e9 + 7;
template <typename T> void chmin(T &a, T b) { a = min(a, b); }
template <typename T> void chmax(T &a, T b) { a = max(a, b); }
int n, k;
vector<vector<P>> G;
vector<int> vis, sz;
ll res;
void szd(int i, int p) {
    sz[i] = 1;
    for (auto &e : G[i]) {
        if (e.first == p || vis[e.first]) {
            continue;
        }
        szd(e.first, i);
        sz[i] += sz[e.first];
    }
}
int findc(int i, int p, int lim) {
    for (auto &e : G[i]) {
        if (e.first == p || vis[e.first]) {
            continue;
        }
        if (sz[e.first] >= lim) {
            return findc(e.first, i, lim);
        }
    }
    return i;
}
void dfs(int i, int p, int a, int b, map<P, ll> &mp) {
    if (a < b) {
        swap(a, b);
    }
    mp[P(a, b)]++;
    for (auto &e : G[i]) {
        if (e.first == p || vis[e.first]) {
            continue;
        }
        if (a == e.second || b == e.second) {
            dfs(e.first, i, a, b, mp);
        } else if (b == -1) {
            dfs(e.first, i, a, e.second, mp);
        }
    }
}
void calc(int v) {
    szd(v, -1);
    int c = findc(v, -1, sz[v] / 2);
    map<P, ll> mp;
    map<ll, ll> cnt, m1;
    ll sum = 0;
    for (auto &e : G[c]) {
        if (vis[e.first]) {
            continue;
        }
        map<P, ll> mpn;
        dfs(e.first, c, e.second, -1, mpn);
        for (auto p : mpn) {
            if (p.first.second == -1) {
                res +=
                    (cnt[p.first.first] + sum - m1[p.first.first]) * p.second;
            } else {
                res += (mp[p.first] + m1[p.first.first] + m1[p.first.second]) *
                       p.second;
            }
        }
        for (auto p : mpn) {
            if (p.first.second == -1) {
                m1[p.first.first] += p.second;
                sum += p.second;
            } else {
                res += p.second;
                cnt[p.first.first] += p.second;
                cnt[p.first.second] += p.second;
                mp[p.first] += p.second;
            }
        }
    }
    vis[c] = 1;
    for (auto &e : G[c]) {
        if (vis[e.first]) {
            continue;
        }
        calc(e.first);
    }
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> k;
    G.resize(n);
    vis.resize(n);
    sz.resize(n);
    for (int i = 0; i < n - 1; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        --a;
        --b;
        --c;
        G[a].eb(b, c);
        G[b].eb(a, c);
    }
    calc(0);
    cout << res << '\n';
}