#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define sc second
#define fr first
#define all(x) x.begin(), x.end()
#define sz(x) (ll) x.size()
#define dbg(x) cerr << #x << ": [ " << x << " ]\n"
typedef long long ll;
typedef pair<int, int> pii;
const int LOG = 22;
const int MAX = 2e5 + 15;
const int INF = 0x3f3f3f3f;
struct Edge{
ll v, c1, c2;
Edge(ll a = 0, ll b = 0, ll c = 0){
v = a, c1 = b, c2 = c;
}
};
ll n, dp[MAX][LOG], dp2[MAX], d[MAX], t[MAX], w1[MAX], w2[MAX], ans;
vector<Edge> adj[MAX];
void dfs(ll u, ll p){
dp[u][0] = p;
for(Edge e : adj[u]){
ll v = e.v, wc = e.c1, wt = e.c2;
if(p == v) continue;
d[v] = d[u] + 1;
w1[v] = wc;
w2[v] = wt;
dfs(v, u);
}
}
ll lca(ll u, ll v){
if(d[v] > d[u]) swap(u, v);
for(int j = LOG - 1; j >= 0; j--)
if(d[u] - (1 << j) >= d[v]) u = dp[u][j];
if(u == v) return v;
for(int j = LOG - 1; j >= 0; j--){
if(dp[u][j] != -1 && dp[u][j] != dp[v][j])
u = dp[u][j], v = dp[v][j];
}
return dp[u][0];
}
void calcDp(ll u, ll p){
for(Edge e : adj[u]){
ll v = e.v, w1 = e.c1, w2 = e.c2;
if(p == v) continue;
calcDp(v, u);
dp2[u] += dp2[v];
}
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
for(int i = 1; i < n; i++){
ll u, v, wc, wt; cin >> u >> v >> wc >> wt;
adj[u].pb(Edge(v, wc, wt));
adj[v].pb(Edge(u, wc, wt));
}
memset(dp, -1, sizeof(dp));
dfs(1, -1);
for(int j = 1; j < LOG; j++){
for(int i = 1; i <= n; i++){
if(dp[i][j - 1] == -1) continue;
dp[i][j] = dp[dp[i][j - 1]][j - 1];
}
}
for(int i = 1; i < n; i++){
ll l = lca(i, i + 1);
dp2[i]++; dp2[i + 1]++, dp2[l] -= 2;
}
calcDp(1, -1);
for(int i = 2; i <= n; i++)
ans += min(w2[i], w1[i] * dp2[i]);
cout << ans << '\n';
return 0;
}
