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#include <bits/stdc++.h>
#define ll long long
#define mp make_pair
#define fi first
#define se second
#define pb push_back
#define pi pair<int, int>
#define mod 1000000007
template<typename T> bool chkmin(T &a, T b){return (b < a) ? a = b, 1 : 0;}
template<typename T> bool chkmax(T &a, T b){return (b > a) ? a = b, 1 : 0;}
ll ksm(ll a, ll b) {if (b == 0) return 1; ll ns = ksm(a, b >> 1); ns = ns * ns % mod; if (b & 1) ns = ns * a % mod; return ns;}
using namespace std;
const int maxn = 200005;
#define vl vector<ll>
const ll inf = 1e18;
int mxinv = 0;
const int hh = 1100;
vl mpl(vl a, vl b) { 
    // max plus product of convex a, b
    // size must be odd
    if (a.size() >= 2 * hh) {
        int md = a.size() / 2;
        a = vl(a.begin() + md - hh, a.begin() + md + hh + 1);
    }
    if (b.size() >= 2 * hh) {
        int md = b.size() / 2;
        b = vl(b.begin() + md - hh, b.begin() + md + hh + 1);
    }
    for (auto &v: a)
        if (v < -inf / 2) v = -inf;
    for (auto &v: b)
        if (v < -inf / 2) v = -inf;
    vl res(a.size() + b.size() - 1);
    fill(res.begin(), res.end(), -inf);
    if (min(a.size(), b.size()) < 10 && 0) {
        for (int i = 0; i < a.size(); i++)
            for (int j = 0; j < b.size(); j++)
                chkmax(res[i + j], a[i] + b[j]);
    }
    else {
        auto inv = [&](int l1, int r1, int l2, int r2) {
            int p[2] = {l1, l2};
            for (int i = l1 + l2; i <= r1 + r2; i++) {
                chkmax(res[i], a[p[0]] + b[p[1]]);
                if (p[0] == r1) p[1] += 1;
                else if (p[1] == r2) p[0] += 1;
                else {
                    if (a[p[0] + 1] - a[p[0]] > b[p[1] + 1] - b[p[1]]) p[0] += 1;
                    else p[1] += 1;
                }
            }
        };
        vector<int> h[2];
        h[0].pb(0); h[1].pb(0);
        for (int i = 1; i < a.size() - 1; i++)
            if (a[i + 1] - a[i] > a[i] - a[i - 1])
                h[0].pb(i);
        for (int i = 1; i < b.size() - 1; i++)
            if (b[i + 1] - b[i] > b[i] - b[i - 1])
                h[1].pb(i);
        chkmax(mxinv, max((int)h[0].size(), (int)h[1].size()));
        h[0].pb(a.size() - 1); h[1].pb(b.size() - 1);
        for (int i = 0; i < h[0].size() - 1; i++)
            for (int j = 0; j < h[1].size() - 1; j++)
                inv(h[0][i], h[0][i + 1], h[1][j], h[1][j + 1]);
    }
    return res; 
}
struct ans {
    vl x[2];
    ans() {x[0] = vl{-inf}, x[1] = vl{-inf};}
};
vl mx(vl a, vl b) { // max of two
    if (a.size() < b.size()) swap(a, b);
    int ma = a.size() / 2, mb = b.size() / 2;
    for (int j = -mb; j <= mb; j++)
        chkmax(a[ma + j], b[mb + j]);
    return a; 
}
ans uni(ans a, ans b) {
    ans res;
    for (int i = 0; i < 2; i++)
        for (int j = 0; j < 2; j++)
            res.x[i ^ j] = mx(res.x[i ^ j], mpl(a.x[i], b.x[j]));
    return res; 
}
ans cur[maxn];
ans cal(int l, int r) {
    if (l == r) return cur[l];
    int mid = (l + r) >> 1;
    return uni(cal(l, mid), cal(mid + 1, r));
}

int n, m;
ll dp[maxn][4];
vector<pi> eg[maxn];
mt19937 rd;
void dfs(int a, int fa) {
    for (int i = 0; i < 4; i++)
        dp[a][i] = -inf;
    for (auto v : eg[a]) {
        if (v.fi == fa) continue;
        dfs(v.fi, a);
    }
    int cnt = 0;
    cur[cnt].x[0] = vl{0}, cur[cnt].x[1] = vl{-inf};
    cnt += 1;
    for (auto v : eg[a]) {
        if (v.fi == fa) continue;
        ans hh;
        hh.x[0].resize(3);
        for (int j = 0; j < 3; j++)
            hh.x[0][j] = -inf;
        for (int t = 0; t < 2; t++) 
            for (int j = 0; j < 4; j++) {
                if ((t == 0) && (j != 0)) continue;
                int ntp = 0, npar = 0;
                if ((t + j) == 2) npar = 1;
                if (t + j == 1) ntp = 1;
                else if (t + j == 3) ntp = -1;
                ll nw = dp[v.fi][j];
                if (t) nw += v.se;
                chkmax(hh.x[npar][hh.x[npar].size() / 2 + ntp], nw);
            }
        cur[cnt++] = hh;
    }
    shuffle(cur, cur + cnt, rd);
    ans cm = cal(0, cnt - 1);
    for (int j = 0; j < 4; j++) {
        int ntp = 0, npar = 0;
        if (j == 1) ntp = 1;
        else 
            if (j == 3) ntp = -1;
        if (j == 2) npar = 1;
        int nsz = cm.x[npar].size() / 2;
        if (nsz >= abs(ntp))
            chkmax(dp[a][j], cm.x[npar][nsz + ntp]);
    }
    //cout << a << ' ' << dp[a][0] << ' ' << cnt << ' ' << cm.x[0].size() << ' ' << cm.x[0][0] << endl;
}
int main() {    
    //freopen("x.out", "r", stdin);
    cin >> n;
    for (int i = 1; i < n; i++) {
        int u, v, w;
        scanf("%d%d%d", &u, &v, &w);
        eg[u].pb(mp(v, w));
        eg[v].pb(mp(u, w));
    }
    dfs(1, 0);
    //cout << mxinv << ' ' << eg[1].size() << endl;
    cout << dp[1][0] << endl;
    //cout << 1.0 * clock() / CLOCKS_PER_SEC << endl;
    return (0-0); // <3 cxr
}