#include <bits/stdc++.h>
using namespace std;
template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl
using ll = long long;
const int maxn = 2e5 + 10;
const int LOG = 18;
int n;
pair<ll,ll> edge[maxn];
vector<pair<int,int>> g[maxn];
int dep[maxn];
int par[LOG+1][maxn];
void dfs(int at, int p) {
for (int i=1; i<LOG; i++) {
par[i][at] = par[i-1][par[i-1][at]];
}
for (auto ed: g[at]) {
int to = ed.second;
if (to == p) continue;
dep[to]=1+dep[at];
par[0][to]=at;
dfs(to,at);
}
}
ll dp[maxn];
int lca(int u, int v) {
if (dep[u]<dep[v]) swap(u,v);
int dx = dep[u]-dep[v];
for (int i=0; i<LOG; i++) {
if (dx>>i&1) {
u = par[i][u];
}
}
if (u==v) return u;
for (int i=LOG-1; i>=0; i--) {
if (par[i][u] != par[i][v]) {
u = par[i][u];
v = par[i][v];
}
}
return par[0][u];
}
ll edUsage[maxn];
void dfs2(int at, int p) {
int edId = -1;
for (auto ed: g[at]) {
int to = ed.second;
if (to==p) {
edId = ed.first;
} else {
dfs2(to, at);
}
}
if (~edId) {
edUsage[edId] += dp[at];
dp[p] += dp[at];
}
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin>>n;
for (int i=0; i<n-1; i++) {
int u,v; cin>>u>>v;
int c0,c1;
cin>>c0>>c1;
g[u].push_back({i,v});
g[v].push_back({i,u});
edge[i] = {c0,c1};
}
dfs(1, 0);
for (int i=1; i<n; i++) {
int j=i+1;
int mid = lca(i,j);
dp[i]++;
dp[j]++;
dp[mid]--;
}
dfs2(1, 0);
ll res = 0;
for (int i=0; i<n-1; i++) {
res += min(edge[i].second, edUsage[i]*edge[i].first);
}
cout<<res<<endl;
return 0;
}
