//Huyduocdithitp
#include <bits/stdc++.h>
typedef long long ll;
#define endl '\n'
#define yes cout<<"YES"<<endl;
#define no cout<<"NO"<<endl;
#define fi first
#define se second
#define pii pair<ll, ll>
#define inf 1e9
#define faster ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define MP make_pair
#define TASK "ghuy4g"
#define start if(fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin);freopen(TASK".out","w",stdout);}
#define LOG 19
#define N 200005
using namespace std;
map<ll, pii> mp[N];
struct Canh {
ll u, v, c1, c2;
} canh[N];
ll n, par[N][LOG + 2], high[N], d[N];
pii cost[N];
vector<ll> adj[N];
void prepare() {
high[0] = -1;
for( int j = 1 ; j <= LOG ; j++ ){
for( int i = 1 ; i <= n; i++ ){
par[i][j] = par[par[i][j-1]][j-1];
}
}
}
ll lca(ll u, ll v){ // mac dinh u > v
if ( high[v] > high[u] ) return lca(v,u);
for( int i = LOG ; i >= 0 ; i-- ) if( high[par[u][i]] >= high[v] ) {
u = par[u][i];
}
if( u == v ) return v;
//gd 2 ;
for( int i = LOG ; i >= 0 ; i-- ){
if( par[u][i] != par[v][i] ){
u = par[u][i];
v = par[v][i];
}
}
return par[u][0];
}
void dfs(ll u, ll parent) {
for (auto v : adj[u]) {
if (v == parent) continue;
par[v][0] = u;
high[v] = high[u] + 1;
dfs(v, u);
}
}
void dfs_cal(ll u, ll parent) {
for (auto v : adj[u]) {
if (v == parent) {
continue;
}
dfs_cal(v, u);
d[u] += d[v];
}
}
signed main(void) {
faster;
cin >> n;
for (int i = 1; i <= n - 1; i ++) {
ll u, v, c1, c2;
cin >> u >> v >> c1 >> c2;
adj[u].push_back(v);
adj[v].push_back(u);
mp[u][v] = mp[v][u] = {c1, c2};
canh[i] = {u, v, c1, c2};
}
dfs(1, 1);
prepare();
for (int i = 1; i <= n - 1; i ++) {
ll x = lca(i, i + 1);
d[i] ++ ;
d[i + 1] ++ ;
d[x] -= 2;
}
dfs_cal(1, 1);
ll ans = 0;
for (int i = 2; i <= n; i ++) {
ll c1 = mp[i][par[i][0]].fi, c2 = mp[i][par[i][0]].se;
ans = ans + min(c1 * d[i], c2);
}
cout << ans;
return 0;
}
