#include <bits/stdc++.h>
using namespace std;

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr); cout.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return std::vector(arg, init);
    else return std::vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

int main() {
#define int int64_t

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

    auto g = vec<tuple<int, int>>(uns, n, 0);
    auto e = vec<tuple<int, int, int>>(uns, n - 1);
    for (int i = 0; i < n - 1; ++i) {
        int a, b, c; cin >> a >> b >> c; --a; --b;
        g[a].emplace_back(b, c);
        g[b].emplace_back(a, c);
        e[i] = { a, b, c };
    }

    auto c = vec<int>(uns, n);
    auto d = vec<bool>(false, n, n);

    auto dfs = [&](int v, int p, auto &&dfs) -> int {
        auto &ans = c[v];

        ans = 0;
        for (auto [next, _] : g[v]) {
            if (next == p) continue;
            ans += dfs(next, v, dfs);
            d[v][next] = true;
        }
        ans += ans == 0;

        return ans;
    };

    dfs(0, -1, dfs);

    for (auto &[a, b, c] : e) {
        if (!d[a][b]) {
            swap(a, b);
        }
    }

    auto value = vec<int>(uns, n - 1);
    auto weight = vec<int>(uns, n - 1);
    for (int i = 0; i < n - 1; ++i) {
        auto [a, b, cost] = e[i];
        value[i] = cost * c[b];
        weight[i] = cost;
    }

    auto dp = vec<int64_t>(0, n, k + 1);
    auto prev = vec<tuple<int, int>>(uns, n, k + 1);

    for (int i = 1; i <= n - 1; ++i) {
        for (int j = 0; j <= k; ++j) {
            if (weight[i - 1] <= j) {
                if (auto v = dp[i - 1][j - weight[i - 1]] + value[i - 1]; dp[i][j] < v) {
                    dp[i][j] = v;
                    prev[i][j] = { i - 1, j - weight[i - 1] };
                }
            }
            if (dp[i][j] < dp[i - 1][j]) {
                dp[i][j] = dp[i - 1][j];
                prev[i][j] = { i - 1, j };
            }
        }
    }

    auto choosed = vec<tuple<int, int>>(uns, 0);

    auto back = [&](int i, int j, auto &&back) -> void {
        if (i == 0 && j == 0) return;

        auto [pi, pj] = prev[i][j];
        back(pi, pj, back);

        if (j != pj && weight[i - 1] <= j) {
            auto [a, b, c] = e[i - 1];
            choosed.emplace_back(a, b);
        }
    };

    back(n - 1, k, back);

    for (auto [a, b] : choosed) {
        for (auto &[c, d, cost] : e) {
            if (a == c && b == d) {
                cost *= 2;
            }
        }
    }

    int64_t ans = 0;
    for (auto [a, b, cost] : e) {
        ans += c[b] * cost;
    }

    cout << ans << endl;
}