#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
using LL = long long;

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

    int n, m;
    cin >> n >> m;
    vector<vector<pair<int, int> > > g(n + 1);
    for(int i = 0; i < n - 1; i++){
        int a, b, c;
        cin >> a >> b >> c;
        g[a].push_back({b, c});
        g[b].push_back({a, c});
    }
    vector<int> c(n + 1);
    for(int i = 1; i <= n; i++) cin >> c[i];

    vector<LL> p;
    p.reserve(n * n);

    for(int i = 1; i <= n; i++){
                
        auto dfs = [&](auto &&dfs, int u, int fa) -> int {
            vector<int> v;
            for(auto [j, w] : g[u]){
                if (j == fa) continue;
                int t = dfs(dfs, j, u) + w;
                v.push_back(t);
            }
            if (v.empty()) return 0;
            sort(v.begin(), v.end(), greater<>());
            for(int j = 1; j < v.size(); j++){
                p.push_back(1LL * c[i] * v[j]);
            }
            return v[0];
        };

        int t = dfs(dfs, i, -1);
        p.push_back(1LL * c[i] * t);
    }
    sort(p.begin(), p.end(), greater<>());
    if (p.size() > m) p.resize(m);
    LL ans = 0;
    for(auto x : p) ans += x;
    cout << ans << '\n';

}
/*#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
using LL = long long;

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

    int n, m;
    cin >> n >> m;
    vector<vector<pair<int, int> > > g(n + 1);
    for(int i = 0; i < n - 1; i++){
        int a, b, c;
        cin >> a >> b >> c;
        g[a].push_back({b, c});
        g[b].push_back({a, c});
    }
    vector<int> c(n + 1);
    for(int i = 1; i <= n; i++) cin >> c[i];

    vector<LL> p;
    p.reserve(n * n);

    for(int i = 1; i <= n; i++){

            return v[0];
        };

        int t = dfs(dfs, i, -1);
        p.push_back(1LL * c[i] * t);
    }
    sort(p.begin(), p.end(), greater<>());
    if (p.size() > m) p.resize(m);
    LL ans = 0;
    for(auto x : p) ans += x;
    cout << ans << '\n';

}*/