#include <bits/extc++.h>
#define int int64_t

using namespace std;
using namespace __gnu_pbds;

const int N = 1e5 + 1;
const int mod = 1e9 + 7;

array<bool, N> used;
array<int, N> sz;
array<vector<pair<int, int>>, N> g;

int recalcSizes(int v, int p = -1) {
    sz[v] = 1;
    for (auto [u, w] : g[v]) {
        if (u != p && !used[u]) {
            sz[v] += recalcSizes(u, v);
        }
    }
    return sz[v];
}

int centroid(int n, int v, int p = -1) {
    for (auto [u, w] : g[v]) {
        if (u != p && !used[u] && sz[u] > n / 2) {
            return centroid(n, u, v);
        }
    }
    return v;
}

void dfs(int v, int p, int& ans, int &sum, int prev_sum, int& cnt, int prev_cnt, int depth) {
    cnt++;
    cnt %= mod;

    sum += depth;
    sum %= mod;

    ans += prev_cnt * depth + prev_sum;
    ans %= mod;

    for (auto [u, w] : g[v]) {
        if (u != p && !used[u]) {
            dfs(u, v, ans, sum, prev_sum, cnt, prev_cnt, depth + w);
        }
    }
}

int centroidDecomposition(int v) {
    recalcSizes(v);

    int ans = 0, sum = 0, cnt = 0;
    for (auto [u, w] : g[v]) {
        if (!used[u]) {
            dfs(u, v, ans, sum, sum, cnt, cnt, w);
        }
    }
    ans += sum;
    ans %= mod;

    used[v] = true;
    for (auto [u, w] : g[v]) {
        if (!used[u]) {
            ans += centroidDecomposition(centroid(sz[u], u));
            ans %= mod;
        }
    }

    return ans;
}

int32_t main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    for (int i = 0; i < n - 1; i++) {
        int v, u;
        cin >> v >> u;
        v--, u--;

        int w;
        cin >> w;

        g[v].emplace_back(u, w);
        g[u].emplace_back(v, w);
    }

    recalcSizes(0);
    cout << centroidDecomposition(centroid(n, 0));
}