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

#define int long long

#define il inline

#define rd read()


const int L = 5e6 + 100, inf = 1e12, mod = 1e9 + 7;
int n, sz[L], ans = 0;
int head[L], edge[L], nxt[L], w[L], now = 0;

il void addEdge(int u, int v, int x) {
    edge[++now] = v;
    w[now] = x;
    nxt[now] = head[u];
    head[u] = now;
}

il void dfs1(int st, int fa) {
    sz[st] = 1;
    for (int i = head[st]; i; i = nxt[i]) {
        int j = edge[i];
        if (j == fa)
            continue;
        dfs1(j, st);
        sz[st] += sz[j];
    }
}

il void dfs2(int st, int fa) {
    for (int i = head[st]; i; i = nxt[i]) {
        int j = edge[i];
        if (j == fa)
            continue;
        ans += abs(n - sz[j] * 2) * w[i];
        // printf("test: %lld %lld : %lld %lld\n", st, j, (n - sz[j] * 2) * w[i], n - sz[j] * 2);
        dfs2(j, st);
    }
}

il int read() {
    int res = 0, f = 1;
    char c = getchar();
    while (c < '0' || c > '9') {
        if (c == '-')
            f = -1;
        c = getchar();
    }
    while (c >= '0' && c <= '9') {
        res = res * 10 + c - 48;
        c = getchar();
    }
    return res * f;
}

signed main() {
    // freopen("test.out", "w", stdout);
    n = rd;
    int u, v, x;
    for (int i = 1; i < n; ++i) {
        u = rd, v = rd, x = rd;
        addEdge(u, v, x), addEdge(v, u, x);
    }
    dfs1(1, 0);
    dfs2(1, 0);
    // for(int i = 1; i <= n; ++ i) printf("%lld :%lld\n", i, sz[i]);
    printf("%lld\n", ans);
    return 0;
}

/*
2
3
0 2
1 2
3 3
3
1 0
2 3
0 10
*/