#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>using namespace std;const int maxn = 1000100;struct edge {    int t, d;     edge* next;}e[maxn * 2], *head[maxn]; int ne = 0;int n, m;void addedge(int f, int t, int d) {    e[ne].t = t, e[ne].d = d, e[ne].next = head[f], head[f] = e + ne ++;  }int sta[maxn], top = 0, size[maxn], dis[maxn];void dfs(int x, int fa) {    sta[++ top] = x; size[x] = 1;    for(edge* p = head[x]; p; p = p-> next) {        if(p-> t != fa) dis[p-> t] = p-> d, dfs(p-> t, x), size[x] += size[p-> t];    }}int int_get() {    int x = 0; char c = (char)getchar(); bool f =0 ;    while(!isdigit(c)) {        if(c == ‘-‘) f = 1;        c = (char)getchar();    }    while(isdigit(c)) {        x = x * 10 + (int)(c - ‘0‘);        c = (char)getchar();    }    if(f) x = -x;    return x;}void read() {    n = int_get();    for(int i = 1; i < n; ++ i) {        int u, v, w;         u = int_get(), v = int_get(), w = int_get();        addedge(u, v, w), addedge(v, u, w);    }}long long ans = 0;void sov() {    dfs(1, 0);    for(int i = top; i >= 2; -- i) {        ans += (long long)(abs(n - 2 * size[sta[i]])) * (long long)dis[sta[i]];    }    printf("%lld\n", ans);}int main() {    //freopen("test.in", "r", stdin);    read(), sov();    return 0;}