#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int INF = 1e9;
const ll LINF = 1e18;
const int N = 2e5 + 5;
struct AdjEdge {
int to, id;
};
struct Edge {
int c1, c2;
};
int n;
vector<AdjEdge> adj[N];
vector<Edge> edges;
int up[18][N];
int tin[N], tout[N], timer;
int edge_to_node[N];
void dfs1(int u, int p) {
tin[u] = ++timer;
up[0][u] = p;
for (int i = 1; i <= 17; i++) {
up[i][u] = up[i - 1][up[i - 1][u]];
}
for (auto e : adj[u]) {
int v = e.to, id = e.id;
if (v == p) continue;
edge_to_node[id] = v;
dfs1(v, u);
}
tout[u] = timer;
}
bool isAncestor(int u, int v) {
return (tin[u] <= tin[v] && tout[v] <= tout[u]);
}
int lca(int u, int v) {
if (isAncestor(u, v)) return u;
if (isAncestor(v, u)) return v;
for (int i = 17; i >= 0; i--) {
if (!isAncestor(up[i][u], v)) {
u = up[i][u];
}
}
return up[0][u];
}
int sum[N];
void dfs2(int u, int p) {
for (auto e : adj[u]) {
int v = e.to;
if (v == p) continue;
dfs2(v, u);
sum[u] += sum[v];
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 0; i < n - 1; i++) {
int u, v, c1, c2;
cin >> u >> v >> c1 >> c2;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
edges.push_back({c1, c2});
}
timer = 0;
dfs1(1, 1);
for (int u = 1; u + 1 <= n; u++) {
int v = u + 1;
sum[u]++;
sum[v]++;
sum[lca(u, v)] -= 2;
}
dfs2(1, 1);
ll ans = 0;
for (int i = 0; i < n - 1; i++) {
ll c1 = edges[i].c1, c2 = edges[i].c2;
int u = edge_to_node[i];
ans += min(sum[u] * c1, c2);
}
cout << ans << '\n';
}
