#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define pb push_back
#define all(x) x.begin(), x.end()
const int N = 2e5 + 10, M = 1e5+10, F = 2147483646, K = 20;
int n, a, b, depth[N], timein[N], lca[4*N][K];
vector<pair<int, pair<ll, ll>>> g[N];
vector<int> euler;
pair<int, int> s[N];
ll ans = 0, m[N], sum = 0;
void dfs(int v, int p, int d){
depth[v] = d;
timein[v] = int(euler.size());
euler.pb(v);
for(auto k: g[v]){
if(k.first != p){
dfs(k.first, v, d + 1);
euler.pb(v);
}
}
}
int mx(int l, int r){
int k = __lg(r - l + 1);
if(depth[lca[l][k]] < depth[lca[r - (1<<k) + 1][k]])
return lca[l][k];
return lca[r - (1<<k) + 1][k];
}
void ans_dfs(int v, int p){
for(auto k: g[v]){
if(k.first != p){
ans_dfs(k.first, v);
ans += min(sum * k.second.first, k.second.second);
// cout << sum << ' ' << v << ' ' << k.first << ' ' << m[v] << '\n';
sum -= m[v];
m[v] = 0;
}
}
++m[s[v].first];
++m[s[v].second];
if(s[v].first != 0) ++sum;
if(s[v].second != 0) ++sum;
}
int main(){
cin.tie(0); ios::sync_with_stdio(0);
cin >> n;
for(int i = 0; i < n - 1; ++i){
ll w1, w2;
cin >> a >> b >> w1 >> w2;
g[a].pb({b, {w1, w2}});
g[b].pb({a, {w1, w2}});
}
for(int i = 1; i <= n; i++) timein[i] = 1e9, s[i] = {0, 0};
dfs(1, 0, 0);
for(int i = 0; i < int(euler.size()); i++) lca[i][0] = euler[i];
for(int j = 1; j < K; ++j){
for(int i = 0; i + (1 << (j-1)) <= int(euler.size()); ++i){
if(depth[lca[i][j - 1]] < depth[lca[i + (1<<(j-1))][j - 1]]) lca[i][j] = lca[i][j - 1];
else lca[i][j] = lca[i + (1<<(j-1))][j - 1];
}
}
for(int i = 1; i < n; i++){
int node = mx(min(timein[i], timein[i + 1]), max(timein[i + 1], timein[i]));
if(node != i)
s[i].second = node;
if(node != i + 1)
s[i + 1].first = node;
}
// for(int i = 1; i <= n; i++) cout << s[i].first << ' ' << s[i].second << '\n';
sum = 0;
ans_dfs(1, 0);
cout << ans;
return 0;
}
