#line 1 "main.cpp"
#pragma region Macros
#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}
#ifdef DEBUG
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
    os << '{';
    for(int i = 0; i < (int)v.size(); i++) {
        if(i) { os << ','; }
        os << v[i];
    }
    os << '}';
    return os;
}
void debugg() { cerr << endl; }
template <class T, class... Args>
void debugg(const T &x, const Args &... args) {
    cerr << " " << x;
    debugg(args...);
}
#define debug(...)                                                             \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]: ", debugg(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif

struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(15);
    }
} __Setup;

using ll = long long;
#define OVERLOAD3(_1, _2, _3, name, ...) name
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define REP1(i, n) for(int i = 0; i < (n); i++)
#define REP2(i, a, b) for(int i = (a); i < int(b); i++)
#define REP(...) OVERLOAD3(__VA_ARGS__, REP2, REP1)(__VA_ARGS__)
#define UNIQUE(v) sort(ALL(v)), (v).erase(unique(ALL(v)), (v).end())
const int INF = 1 << 30;
const ll LLINF = 1LL << 60;
constexpr int MOD = 1000000007;
constexpr int MOD2 = 998244353;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

void Case(int i) { cout << "Case #" << i << ": "; }
int popcount(int x) { return __builtin_popcount(x); }
ll popcount(ll x) { return __builtin_popcountll(x); }
#pragma endregion Macros

#line 1 "/home/siro53/kyo-pro/compro_library/math/modint.hpp"
template <int mod> struct ModInt {
    int x;
    ModInt() : x(0) {}
    ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
    ModInt &operator+=(const ModInt &p) {
        if((x += p.x) >= mod)
            x -= mod;
        return *this;
    }
    ModInt &operator-=(const ModInt &p) {
        if((x += mod - p.x) >= mod)
            x -= mod;
        return *this;
    }
    ModInt &operator*=(const ModInt &p) {
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }
    ModInt &operator/=(const ModInt &p) {
        *this *= p.inv();
        return *this;
    }
    ModInt operator-() const { return ModInt(-x); }
    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
    bool operator==(const ModInt &p) const { return x == p.x; }
    bool operator!=(const ModInt &p) const { return x != p.x; }
    ModInt inv() const {
        int a = x, b = mod, u = 1, v = 0, t;
        while(b > 0) {
            t = a / b;
            swap(a -= t * b, b);
            swap(u -= t * v, v);
        }
        return ModInt(u);
    }
    ModInt pow(int64_t n) const {
        ModInt ret(1), mul(x);
        while(n > 0) {
            if(n & 1)
                ret *= mul;
            mul *= mul;
            n >>= 1;
        }
        return ret;
    }
    friend ostream &operator<<(ostream &os, const ModInt &p) {
        return os << p.x;
    }
    friend istream &operator>>(istream &is, ModInt &a) {
        int64_t t;
        is >> t;
        a = ModInt<mod>(t);
        return (is);
    }
    static int get_mod() { return mod; }
};
#line 76 "main.cpp"
using mint = ModInt<MOD>;
#line 1 "/home/siro53/kyo-pro/compro_library/graph/re_rooting.hpp"
template<class S, S (*op)(S, int), S (*merge)(S, S), S (*op2)(S, int), S (*e)()>
class re_rooting {
private:
    int N;
    vector<vector<int>> G;
    vector<vector<S>> dp;

    S dfs1(int u, int p) {
        S res = e();
        for(int i = 0; i < (int)G[u].size(); i++) {
            if(G[u][i] == p) continue;
            int v = G[u][i];
            dp[u][i] = dfs1(v, u);
            res = merge(res, op(dp[u][i], v));
        }
        return op2(res, u);
    }

    void dfs2(int u, int p, S from_par) {
        int sz = (int)G[u].size();
        for(int i = 0; i < sz; i++) {
            if(G[u][i] == p) {
                dp[u][i] = from_par;
                break;
            }
        }
        vector<S> rsum(sz + 1);
        rsum[sz] = e();
        for(int i = sz-1; i >= 0; i--) {
            rsum[i] = merge(rsum[i+1], op(dp[u][i], G[u][i]));
        }
        S lsum = e();
        for(int i = 0; i < sz; i++) {
            int v = G[u][i];
            if(v != p) {
                S val = merge(lsum, rsum[i+1]);
                dfs2(v, u, op2(val, u));
            }
            lsum = merge(lsum, op(dp[u][i], v));
        }
    }

    void build(int root) {
        for(int i = 0; i < N; i++) dp[i].resize(G[i].size());
        dfs1(root, -1);
        dfs2(root, -1, e());
    }
    
public:
    re_rooting(int N): N(N), G(N), dp(N) {}
    re_rooting(const vector<vector<int>>& G): N(G.size()), G(G), dp(G.size()) {}

    void add_edge(int u, int v) {
        G[u].emplace_back(v);
        G[v].emplace_back(u);
    }

    vector<S> solve(int root = 0) {
        build(root);
        vector<S> ans(N);
        for(int u = 0; u < N; u++) {
            S res = e();
            for(int i = 0; i < (int)G[u].size(); i++) {
                res = merge(res, op(dp[u][i], G[u][i]));
            }
            ans[u] = op2(res, u);
        }
        return ans;
    }
};

template<class T>
struct Edge {
    int from, to;
    T cost;
    Edge() = default;
    Edge(int from, int to, T cost): from(from), to(to), cost(cost) {}
    operator int() const { return to; }
};

template<class S, class Cost, S (*op)(S, Edge<Cost>), S (*merge)(S, S), S (*op2)(S, int), S (*e)()>
class re_rooting_edge {
private:
    int N;
    vector<vector<Edge<Cost>>> G;
    vector<vector<S>> dp;

    S dfs1(int u, int p) {
        S res = e();
        for(int i = 0; i < (int)G[u].size(); i++) {
            int v = G[u][i];
            if(v == p) continue;
            dp[u][i] = dfs1(v, u);
            res = merge(res, op(dp[u][i], G[u][i]));
        }
        return op2(res, u);
    }

    void dfs2(int u, int p, S from_par) {
        int sz = (int)G[u].size();
        for(int i = 0; i < sz; i++) {
            if(G[u][i] == p) {
                dp[u][i] = from_par;
                break;
            }
        }
        vector<S> rsum(sz + 1);
        rsum[sz] = e();
        for(int i = sz-1; i >= 0; i--) {
            rsum[i] = merge(rsum[i+1], op(dp[u][i], G[u][i]));
        }
        S lsum = e();
        for(int i = 0; i < sz; i++) {
            int v = G[u][i];
            if(v != p) {
                S val = merge(lsum, rsum[i+1]);
                dfs2(v, u, op2(val, u));
            }
            lsum = merge(lsum, op(dp[u][i], G[u][i]));
        }
    }

    void build(int root) {
        for(int i = 0; i < N; i++) dp[i].resize(G[i].size());
        dfs1(root, -1);
        dfs2(root, -1, e());
    }

public:
    re_rooting_edge(int N): N(N), G(N), dp(N) {}
    re_rooting_edge(const vector<vector<Edge<Cost>>>& G): N(G.size()), G(G), dp(G.size()) {}

    void add_edge(int u, int v, Cost cost) {
        G[u].emplace_back(u, v, cost);
        G[v].emplace_back(v, u, cost);
    }

    vector<S> solve(int root = 0) {
        build(root);
        vector<S> ans(N);
        for(int u = 0; u < N; u++) {
            S res = e();
            for(int i = 0; i < (int)G[u].size(); i++) {
                res = merge(res, op(dp[u][i], G[u][i]));
            }
            ans[u] = op2(res, u);
        }
        return ans;
    }
};
#line 78 "main.cpp"

using S = tuple<mint, mint, mint>;
using Cost = mint;

S op(S x, Edge<Cost> e) {
    auto [s2, d, sz] = x;
    return S(d*2*e.cost + s2 + e.cost*e.cost*(sz+1), d+e.cost*(sz+1), sz+1);
}
S merge(S x, S y) {
    auto [s2x, dx, szx] = x;
    auto [s2y, dy, szy] = y;
    return S(s2x + s2y, dx + dy, szx + szy);
}
S op2(S x, int id) {
    return x;
}
S e() { return {0, 0, 0}; }

int main() {
    int N;
    cin >> N;
    re_rooting_edge<S, Cost, op, merge, op2, e> re(N);
    REP(i, N-1) {
        int u, v, w;
        cin >> u >> v >> w;
        u--; v--;
        re.add_edge(u, v, w);
    }
    auto dp = re.solve();
    mint ans = 0;
    REP(i, N) ans += get<0>(dp[i]);
    ans /= 2;
    cout << ans << endl;
}