#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pair pair<int,int>
template<class T> void maximize(T& a,const T& b) {if (a < b) a = b;}
template<class T> void minimize(T& a,const T& b) {if (a > b) a = b;}
template<class T> T PO2(T x) {return (1 << x);}
#define fi first
#define sc second
#define mset(c, x) memset(c, x, sizeof(c))
#define __11HA7_KZ2__ signed main()
int dx[8] = {0, 1, 0,-1, 1, 1,-1,-1};
int dy[8] = {1, 0,-1, 0, 1,-1,-1, 1};
const int N = 2e5;
const int INF = 1e9;
const ll LINF = 1e18;
const int MOD = 1e9 + 7;
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
int n;
int tin[N+15], tout[N+15], timer;
vector <pair> adj[N+15];
int up[20][N+15], egde_id[N+15];
ll sum[N+15];
struct Edge {
int idx, c1, c2;
};
vector <Edge> edges;
void dfs1(int u, int p) {
tin[u] = ++timer;
up[0][u] = p;
for (int k=1; k <= 17; k++) {
up[k][u] = up[k-1][up[k-1][u]];
}
for (auto it : adj[u]) {
int v = it.fi, idx = it.sc;
if (v != p) {
egde_id[idx] = v;
dfs1(v, u);
}
}
tout[u] = timer;
}
void dfs2(int u, int p) {
for (auto it : adj[u]) {
int v = it.fi;
if (v != p) {
dfs2(v, u);
sum[u] += sum[v];
}
}
}
bool isAncestor(int u, int v) {
return tin[u] <= tin[v] and tout[v] <= tout[u];
}
int lca(int u, int v) {
if (isAncestor(u, v)) return u;
if (isAncestor(v, u)) return v;
for (int k=17; k >= 0; k--) {
if (!isAncestor(up[k][u], v)) {
u = up[k][u];
}
}
return up[0][u];
}
void update(int u, int v) {
int lca_uv = lca(u, v);
sum[u]++;
sum[v]++;
sum[lca_uv] -= 2;
}
__11HA7_KZ2__
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for (int i=1; i < n; 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({i, c1, c2});
}
dfs1(1, 1);
for (int i=1; i < n; i++) {
update(i, i+1);
}
dfs2(1, 1);
ll ans = 0;
for (auto it : edges) {
int idx = it.idx, c1 = it.c1, c2 = it.c2;
ans += min(sum[egde_id[idx]] * c1, 1ll * c2);
}
cout << ans;
}
