#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<numeric>
#include<cmath>
#include<utility>
#include<tuple>
#include<cstdint>
#include<cstdio>
#include<iomanip>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<deque>
#include<unordered_map>
#include<unordered_set>
#include<bitset>
#include<cctype>
#include<chrono>
#include<random>
#include<cassert>
#include<cstddef>
#include<iterator>
#include<string_view>
#include<type_traits>

#ifdef LOCAL
#  include "debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

using namespace std;
#define rep(i,n) for(int i=0; i<(n); i++)
#define rrep(i,n) for(int i=(n)-1; i>=0; i--)
#define FOR(i,a,b) for(int i=(a); i<(b); i++)
#define RFOR(i,a,b) for(int i=(b-1); i>=(a); i--)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define pb push_back
using ll = long long;
using D = double;
using LD = long double;
using P = pair<int, int>;
template<typename T> using PQ = priority_queue<T,vector<T>>;
template<typename T> using minPQ = priority_queue<T, vector<T>, greater<T>>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
void yesno(bool flag) {cout << (flag?"Yes":"No") << "\n";}

template<typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << p.first << " " << p.second;
    return os;
}
template<typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
    is >> p.first >> p.second;
    return is;
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    int s = (int)v.size();
    for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i];
    return os;
}
template<typename T>
istream &operator>>(istream &is, vector<T> &v) {
    for (auto &x : v) is >> x;
    return is;
}
void in() {}
template<typename T, class... U>
void in(T &t, U &...u) {
    cin >> t;
    in(u...);
}
void out() { cout << "\n"; }
template<typename T, class... U, char sep = ' '>
void out(const T &t, const U &...u) {
    cout << t;
    if (sizeof...(u)) cout << sep;
    out(u...);
}
void outr() {}
template<typename T, class... U, char sep = ' '>
void outr(const T &t, const U &...u) {
    cout << t;
    outr(u...);
}

template<int mod> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % mod) {
        if (val < 0) val += mod;
    }
    constexpr int getmod() { return mod; }
    constexpr Fp operator - () const noexcept {
        return val ? mod - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= mod) val -= mod;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += mod;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % mod;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = mod, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % mod;
        if (val < 0) val += mod;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr istream& operator >> (istream &is, const Fp<mod>& x) noexcept {
        int val; is >> val;
        x = Fp<mod>(val);
        return is;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<mod>& x) noexcept {
        return os << x.val;
    }
    friend constexpr Fp<mod> modpow(const Fp<mod> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};

const int mod = 1e9+7;
// const int mod = 998244353;
using mint = Fp<mod>;

const int MAX_N = 200005;

struct var {
    mint dp1, dp2;
    int sz;
    var(mint dp1 = 0, mint dp2 = 0, int sz = 0): dp1(dp1), dp2(dp2), sz(sz) {}

    var merge(const var &a, mint w) const {
        mint ndp1 = dp1 + a.dp1 + w*a.sz;
        mint ndp2 = dp2 + a.dp2 + a.dp1*w*2 + w*w*a.sz;
        int nsz = sz + a.sz;
        return {ndp1, ndp2, nsz};
    }
    var addRoot() const {
        return {dp1, dp2, sz+1};
    }
};

vector<P> g[MAX_N];
vector<var> dp[MAX_N];
var ans[MAX_N];

var dfs1(int v, int p = -1) {
    var dpsum;
    dp[v] = vector<var> (g[v].size());

    rep(i, g[v].size()) {
        int u = g[v][i].first;
        if(u == p) continue;
        mint w = g[v][i].second;
        dp[v][i] = dfs1(u, v);
        dpsum = dpsum.merge(dp[v][i], w);
    }
    return dpsum.addRoot();
}

void dfs2(int v, const var& dpParent = var(), int p = -1) {
    int deg = g[v].size();
    rep(i, deg) if(g[v][i].first == p) dp[v][i] = dpParent;

    vector<var> dpSum_Left(deg+1), dpSum_Right(deg+1);
    rep(i,deg) {
        mint w = g[v][i].second;
        dpSum_Left[i+1] = dpSum_Left[i].merge(dp[v][i], w);
    }
    rrep(i, deg) {
        mint w = g[v][i].second;
        dpSum_Right[i] = dpSum_Right[i+1].merge(dp[v][i],w);
    }

    ans[v] = dpSum_Left[deg].addRoot();

    rep(i,deg) {
        int u = g[v][i].first;
        if(u == p) continue;
        var d = dpSum_Left[i].merge(dpSum_Right[i+1],0);
        dfs2(u, d.addRoot(), v);
    }
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; in(n);
    rep(i,n-1) {
        int a,b,c; in(a,b,c); a--; b--;
        g[a].pb({b,c}); g[b].pb({a,c});
    }
    dfs1(0);
    dfs2(0);
    mint res = 0;
    rep(i,n) res += ans[i].dp2;
    res /= 2;
    out(res);
}