#include <bits/stdc++.h>
using namespace std;
#define endl "\n"
#define int long long
#define all(x) (x).begin(), (x).end()
#define debug(x) cout << #x << ": " << x << endl
#define pb push_back
#define eb emplace_back
#define vi vector<int>
#define rep(i,a,b) for(int i=(int)(a); i < (int)(b); i++)
typedef long long ll;
using iiii = array<int, 4>;
const int oo = 0x3f3f3f3f3f3f3f3f;
const int MAXN = 2e5+2;
vector<vector<int>> g(MAXN);
map<pair<int,int>, int> cost_each, cost_free;
vector<int> tin(2*MAXN), tout(2*MAXN);
vector<vector<int>> up(MAXN, vector<int>(20));
int TIMER = 0;
vector<int> ans(MAXN, 0);
vector<int> cost_each_vertex(MAXN), cost_free_vertex(MAXN);
int res = 0;
void dfs(int u=0, int p=0) {
tin[u] = TIMER++;
cost_each_vertex[u] = cost_each[{u, p}];
cost_free_vertex[u] = cost_free[{u, p}];
up[u][0] = p;
for(int i = 1; i < 20; i++)
up[u][i] = up[up[u][i-1]][i-1];
for(auto v: g[u]) if(v != p)
dfs(v, u);
tout[u] = TIMER++;
/*
cout << "---------- db -----------\n";
cout << "u = " << u << endl;
cout << "tin[u] = " << tin[u] << endl;
cout << "set " << query(tin[u], tin[u]) << endl;
cout << "tout[u] = " << tout[u] << endl;
cout << "set " << query(tout[u], tout[u]) << endl;
*/
}
int is_ancestor(int u, int v) {
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca(int u, int v) {
if(is_ancestor(u, v)) {
ans[u]--;
ans[v]++;
return u;
}
if(is_ancestor(v, u)) {
ans[v]--;
ans[u]++;
return v;
}
ans[u]++;
ans[v]++;
for(int i = 19; i >= 0; i--) {
if(!is_ancestor(up[u][i], v))
u = up[u][i];
}
ans[up[u][0]] -= 2;
return up[u][0];
}
void compute_ans(int u=1, int p=0) {
for(auto v: g[u]) if(v != p) {
compute_ans(v, u);
ans[u] += ans[v];
}
res += min(ans[u]*cost_each_vertex[u], cost_free_vertex[u]);
}
void solve() {
int n;
cin >> n;
vector<iiii> edges(n-1);
for(auto& [a, b, c, d]: edges) {
cin >> a >> b >> c >> d;
g[a].push_back(b);
g[b].push_back(a);
cost_each[{a, b}] = c;
cost_each[{b, a}] = c;
cost_free[{a, b}] = d;
cost_free[{b, a}] = d;
}
g[0].push_back(1);
dfs();
for(int i = 1; i+1 <= n; i++) {
lca(i, i+1);
}
compute_ans();
cout << res << '\n';
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int t = 1;
// cin >> t;
while(t--) solve();
return 0;
}
