//@formatter:off
#include<bits/stdc++.h>
#define overload4(_1,_2,_3,_4,name,...) name
#define rep1(i,n) for (ll i = 0; i < ll(n); ++i)
#define rep2(i,s,n) for (ll i = ll(s); i < ll(n); ++i)
#define rep3(i,s,n,d) for(ll i = ll(s); i < ll(n); i+=d)
#define rep(...) overload4(__VA_ARGS__,rep3,rep2,rep1)(__VA_ARGS__)
#define rrep(i,n) for (ll i = ll(n)-1; i >= 0; i--)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define pb push_back
#define eb emplace_back
#define vi vector<int>
#define vvi vector<vector<int>>
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vd vector<double>
#define vvd vector<vector<double>>
#define vs vector<string>
#define vc vector<char>
#define vvc vector<vector<char>>
#define vb vector<bool>
#define vvb vector<vector<bool>>
#define vp vector<P>
#define vvp vector<vector<P>>
#ifdef __LOCAL
#define debug(...) { cout << #__VA_ARGS__; cout << ": "; print(__VA_ARGS__); }
#else
#define debug(...) void(0)
#endif
#define INT(...) int __VA_ARGS__;scan(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;scan(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;scan(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;scan(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;scan(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__;scan(__VA_ARGS__)
using namespace std;
using ll = long long;
using P = pair<int,int>;
using LP = pair<ll,ll>;
template<class S,class T> istream& operator>>(istream &is,pair<S,T> &p) { return is >> p.first >> p.second; }
template<class S,class T> ostream& operator<<(ostream &os,const pair<S,T> &p) { return os<<'{'<<p.first<<","<<p.second<<'}'; }
template<class T> istream& operator>>(istream &is,vector<T> &v) { for(T &t:v){is>>t;} return is; }
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) { os<<'[';rep(i,v.size())os<<v[i]<<(i==int(v.size()-1)?"":","); return os<<']'; }
void Yes(bool b) { cout << (b ? "Yes" : "No") << '\n'; }
void YES(bool b) { cout << (b ? "YES" : "NO") << '\n'; }
template<class T> void fin(T a) { cout << a << '\n'; exit(0); }
template<class T> bool chmin(T& a,T b) {if(a > b){a = b; return true;} return false;}
template<class T> bool chmax(T& a,T b) {if(a < b){a = b; return true;} return false;}
void scan(){}
template <class Head, class... Tail> void scan(Head& head, Tail&... tail){ cin >> head; scan(tail...); }
template<class T> void print(const T& t){ cout << t << '\n'; }
template <class Head, class... Tail> void print(const Head& head, const Tail&... tail){ cout<<head<<' '; print(tail...); }
const int inf = 1001001001;
const ll linf = 1001001001001001001;
//@formatter:on

constexpr int mod = 1000000007;

//constexpr int mod = 998244353;
struct mint {
    ll x;
    
    constexpr mint(ll x = 0) : x((x % mod + mod) % mod) {}
    
    constexpr mint operator-() const { return mint(-x); }
    
    constexpr mint &operator+=(const mint &a) {
        if ((x += a.x) >= mod) x -= mod;
        return *this;
    }
    
    constexpr mint &operator++() { return *this += mint(1); }
    
    constexpr mint &operator-=(const mint &a) {
        if ((x += mod - a.x) >= mod) x -= mod;
        return *this;
    }
    
    constexpr mint &operator--() { return *this -= mint(1); }
    
    constexpr mint &operator*=(const mint &a) {
        (x *= a.x) %= mod;
        return *this;
    }
    
    constexpr mint operator+(const mint &a) const {
        mint res(*this);
        return res += a;
    }
    
    constexpr mint operator-(const mint &a) const {
        mint res(*this);
        return res -= a;
    }
    
    constexpr mint operator*(const mint &a) const {
        mint res(*this);
        return res *= a;
    }
    
    constexpr mint pow(ll t) const {
        mint res = mint(1), a(*this);
        while (t > 0) {
            if (t & 1) res *= a;
            t >>= 1;
            a *= a;
        }
        return res;
    }
    
    // for prime mod
    constexpr mint inv() const { return pow(mod - 2); }
    
    constexpr mint &operator/=(const mint &a) { return *this *= a.inv(); }
    
    constexpr mint operator/(const mint &a) const {
        mint res(*this);
        return res /= a;
    }
};

ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

bool operator==(const mint &a, const mint &b) { return a.x == b.x; }

bool operator!=(const mint &a, const mint &b) { return a.x != b.x; }

bool operator==(const mint &a, const int &b) { return a.x == b; }

bool operator!=(const mint &a, const int &b) { return a.x != b; }

template<typename T, typename MERGE, typename ADDROOT, typename ADDEDGE>
class rerooting {
    int n;
    vvp tree;
    T identity;
    MERGE merge;
    ADDROOT addRoot;
    ADDEDGE addEdge;
    vector<vector<T>> dp;
    vector<T> ans;
    
    T dfs(int v = 0, int p = -1) {
        T sum = identity;
        dp[v].resize(tree[v].size());
        rep(i, tree[v].size()) {
            auto[u, w] = tree[v][i];
            if (u == p) continue;
            dp[v][i] = dfs(u, v);
            sum = merge(sum, addEdge(dp[v][i], w));
        }
        return addRoot(sum);
    }
    
    void dfs2(T dpP, int v = 0, int p = -1) {
        int sz = tree[v].size();
        rep(i, sz) if (tree[v][i].first == p) dp[v][i] = dpP;
        vector<T> sumL(sz + 1, identity), sumR(sz + 1, identity);
        rep(i, sz) sumL[i + 1] = merge(sumL[i], addEdge(dp[v][i], tree[v][i].second));
        rrep(i, sz) sumR[i] = merge(sumR[i + 1], addEdge(dp[v][i], tree[v][i].second));
        ans[v] = addRoot(sumL[sz]);
        rep(i, sz) {
            auto[u, w] = tree[v][i];
            if (u == p) continue;
            T t = merge(sumL[i], sumR[i + 1]);
            dfs2(addRoot(t), u, v);
        }
    }
    
    void init() {
        dfs();
        dfs2(identity);
    }

public:
    rerooting(int n, vvp tree, T identity, MERGE merge, ADDROOT addRoot, ADDEDGE addEdge)
        : n(n), tree(tree), identity(identity), merge(merge), addRoot(addRoot), addEdge(addEdge), dp(n), ans(n) {
        init();
    };
    
    T get_ans(int i) {
        return ans[i];
    }
};

struct state {
    mint sq_sum, sum;
    int cnt;
    
    state(mint sq_sum = 0, mint sum = 0, int cnt = 0) : sq_sum(sq_sum), sum(sum), cnt(cnt) {}
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    INT(n);
    vvp G(n);
    rep(_, n - 1) {
        INT(u, v, w);
        u--;
        v--;
        G[u].eb(v, w);
        G[v].eb(u, w);
    }
    auto merge = [](const state &a, const state &b) {
        return state(a.sq_sum + b.sq_sum, a.sum + b.sum, a.cnt + b.cnt);
    };
    auto addRoot = [](const state &a) {
        return state(a.sq_sum, a.sum, a.cnt + 1);
    };
    auto addEdge = [](const state &a, int weight) {
        return state(a.sq_sum + a.sum * weight * 2 + mint(weight) * weight * a.cnt, a.sum + mint(weight) * a.cnt,
                     a.cnt);
    };
    rerooting<state, decltype(merge), decltype(addRoot), decltype(addEdge)> rt(n, G, state(0, 0, 0), merge, addRoot,
                                                                               addEdge);
    mint ans = 0;
    rep(i, n) ans += rt.get_ans(i).sq_sum;
    print(ans / 2);
}