#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={-1,0,1,0,1,1,-1,-1};
const ll dx[8]={0,-1,0,1,1,-1,1,-1};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}



const int mod = 1000000007;
const int max_n = 200005;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
  bool operator==(const mint &p) const { return x == p.x; }
  bool operator!=(const mint &p) const { return x != p.x; }
  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
istream& operator>>(istream& is, mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}


struct Edge{
    ll to,weight;
};
template<class T>
class Rerooting{
    public:
    int n;
    T def;
    function<T(T,T)> merge;
    function<T(T,ll)> addroot;
    vector<vector<Edge>> g;
    vector<vector<T>> dp;
    public:
    vector<T> ans;
    Rerooting(int _n,T _def,function<T(T,T)> _merge,function<T(T,ll)> _addroot)
    :n(_n),def(_def),merge(_merge),addroot(_addroot)
    {
        g=vector<vector<Edge>>(n);
        dp=vector<vector<T>>(n);
        ans=vector<T>(n,def);
    }
    void add_edge(int a,Edge e){
        g[a].pb(e);
    }

    T dfs(int v=0,int par=-1){
        T ret=def;
        dp[v].resize(g[v].size());
        rep(i,g[v].size()){
            if(g[v][i].to==par){
              continue;
            }
            dp[v][i]=addroot(dfs(g[v][i].to,v),g[v][i].weight);
            ret=merge(ret,dp[v][i]);
        }
        return ret;
    }

    void bfs(int v,T val,int par=-1){
        int deg=g[v].size();
        rep(i,deg){
            if(g[v][i].to==par)dp[v][i]=val;
        }
        vector<T> dpl(deg+1,def),dpr(deg+1,def);
        rep(i,deg)dpl[i+1]=merge(dpl[i],dp[v][i]);
        per(i,deg)dpr[i]=merge(dpr[i+1],dp[v][i]);
        ans[v]=dpl[deg];
        rep(i,deg){
            int nv=g[v][i].to;
            if(nv==par)continue;
            bfs(nv,addroot(merge(dpl[i],dpr[i+1]),g[v][i].weight),v);
        }
    }
};

struct val{
    mint sq,sum,len;
};
int main(){
    ll n;cin >> n;
    auto mg=[](val a,val b){
        a.sq+=b.sq;a.sum+=b.sum;a.len+=b.len;
        return a;
    };
    auto addroot=[](val a,ll b){
        a.sq+=a.sum*2*b+(a.len+1)*b*b;
        a.sum+=(a.len+1)*b;
        a.len+=1;
        return a;
    };
    val def={0,0,0};
    Rerooting<val> g(n,def,mg,addroot);
    rep(i,n-1){
        ll a,b,w;cin >> a >> b >> w;a--;b--;
        g.add_edge(a,{b,w});
        g.add_edge(b,{a,w});
    }
    g.dfs(0);
    g.bfs(0,def);
    mint ans=0;
    rep(i,n)ans+=g.ans[i].sq;
    cout << ans/2 <<endl;
}