#line 2 "/home/defineprogram/Desktop/Library/template/template.cpp"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, n) for (int i = 0; i < n; i++)
#define REP(i, n) for (int i = 1; i < n; i++)
#define rev(i, n) for (int i = n - 1; i >= 0; i--)
#define all(v) v.begin(), v.end()
#define P pair<ll, ll>
#define len(s) (ll) s.size()

template <class T, class U>
inline bool chmin(T &a, U b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <class T, class U>
inline bool chmax(T &a, U b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
constexpr ll inf = 3e18;
#line 3 "/home/defineprogram/Desktop/Library/math/extgcd.cpp"

ll extGCD(ll a, ll b, ll &x, ll &y) {
    if (!b) {
        x = 1;
        y = 0;
        return a;
    }
    ll d = extGCD(b, a % b, y, x);
    y -= a / b * x;
    return d;
}

ll modinv(ll a, ll m) {
    ll x, y;
    extGCD(a, m, x, y);
    return (x % m + m) % m;
}
#line 4 "/home/defineprogram/Desktop/Library/math/modint.cpp"

template <int MOD>
struct mint {
    int32_t n;
    mint() : n(0) {}
    mint(ll x) : n(x >= 0 ? x % MOD : (MOD - (-x) % MOD) % MOD) {}

    mint &operator+=(const mint &p) {
        if ((n += p.n) >= MOD) n -= MOD;
        return *this;
    }
    mint &operator-=(const mint &p) {
        if ((n += MOD - p.n) >= MOD) n -= MOD;
        return *this;
    }
    mint &operator*=(const mint &p) {
        n = 1ll * n * p.n % MOD;
        return *this;
    }
    mint &operator/=(const mint &p) {
        *this *= p.inverse();
        return *this;
    }
    mint operator-() const { return mint(-n); }
    mint operator+(const mint &p) const { return mint(*this) += p; }
    mint operator-(const mint &p) const { return mint(*this) -= p; }
    mint operator*(const mint &p) const { return mint(*this) *= p; }
    mint operator/(const mint &p) const { return mint(*this) /= p; }
    bool operator==(const mint &p) const { return n == p.n; }
    bool operator!=(const mint &p) const { return n != p.n; }

    friend ostream &operator<<(ostream &os, const mint &p) {
        return os << p.n;
    }
    friend istream &operator>>(istream &is, mint &p) {
        int x;
        is >> x;
        p = mint(x);
        return is;
    }
    mint pow(int64_t x) const {
        mint res(1), mul(n);
        while (x > 0) {
            if (x & 1) res *= mul;
            mul *= mul;
            x >>= 1;
        }
        return res;
    }
    mint inverse() const {
        return mint(modinv(n,MOD));
    }
};
/*
@brief mod int
@docs docs/modint.md
*/
#line 3 "main.cpp"
constexpr int mod=1e9+7;
using modint=mint<mod>;

int N;
vector<pair<int,modint>>G[1<<18];
modint dp1[1<<18],dp2[1<<18];
modint cld[1<<18];
modint ans=0;
void dfs1(int x,int p){
    cld[x]+=1;
    for(auto i:G[x])if(i.first!=p){
        dfs1(i.first,x);
        dp1[x]+=dp1[i.first]+i.second*cld[i.first];
        cld[x]+=cld[i.first];
        ans+=i.second*i.second*cld[i.first]*(modint(N)-cld[i.first]);
    }
}
void dfs2(int x,int p){
    for(auto i:G[x])if(i.first!=p){
        modint par=dp2[x]-dp1[i.first]-i.second*cld[i.first];
        ans+=(par*cld[i.first]+dp1[i.first]*(modint(N)-cld[i.first]))*i.second;
        dp2[i.first]=dp1[i.first]+par+i.second*(modint(N)-cld[i.first]);
        dfs2(i.first,x);
    }
}
int main() {
    cin.tie(0); ios::sync_with_stdio(false);
    cin>>N;
    rep(i,N-1){
        int a,b,c;cin>>a>>b>>c;a--;b--;
        G[a].push_back({b,c});
        G[b].push_back({a,c});
    }
    dfs1(0,0);
    dp2[0]=dp1[0];
    dfs2(0,0);
    cout<<ans<<"\n";
}