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

const int N = 1e5 + 500;

int D[N], pr[N];
vector <pair <int, int> > g[N];
int n;
map <pair <int, int>, int> d, bad, d1;

int bfs(int start) {
    for (int i = 1; i <= n; i++) {
        D[i] = 1e18;
        pr[i] = -1;
    }
    D[start] = 0;
    set <pair <int, int> > q;
    q.insert({0, start});
    while ((int)q.size()) {
        int v = q.begin() -> second; q.erase(q.begin());
        for (auto [to, w] : g[v]) {
            int W = d1[{v, to}];
            if (D[to] > D[v] + W) {
                D[to] = D[v] + W;
                pr[to] = v;
                q.insert({D[to], to});
            }
        }
    }
    int mx = 1;
    for (int i = 1; i <= n; i++) {
        if (D[i] > D[mx]) {
            mx = i;
        }
    }
    return mx;
}

int restore(int end) {
    int sum = 0;
    while (end != -1) {
        int from = pr[end];
        bad[{from, end}] = bad[{end, from}] = 1;
        sum += d[{from, end}];
        d1[{from, end}] = 0;
        d1[{end, from}] = 0;
        end = from;
    }
    return sum;
}


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n;

    for (int i = 0; i < n - 1; i++) {
        int a, b, w;
        cin >> a >> b >> w;
        d[{a, b}] = w;
        d1[{a, b}] = w;
        d[{b, a}] = w;
        d1[{b, a}] = w;
        g[a].push_back({b, w});
        g[b].push_back({a, w});
    }

    int a = bfs(1);
    int b = bfs(a);
    int ans = 0;
    ans += restore(b);
    a = bfs(1);
    b = bfs(a);
    ans += restore(b);

    int sum = 0;
    for (auto [p, v] : d) {
        if (bad.count(p)) {
            continue;
        }
        sum += v;
    }
    cout << ans + sum;
}