#include <bits/stdc++.h>
using namespace std;
#define nl "\n"
#define nf endl
#define ll long long
#define pb push_back
#define _ << ' ' <<
#define INF (ll)1e18
#define mod 998244353
#define maxn 200010
ll i, i1, j, k, k1, t, n, m, res, flag[10], a, b;
ll w1, w2, wu[maxn][2], pr[maxn], dp[maxn];
bool vis[maxn];
vector<array<ll, 3>> adj[maxn];
vector<ll> qdg[maxn];
ll find(ll x) {
if (pr[x] == x) return x;
return pr[x] = find(pr[x]);
}
void onion(ll a, ll b) { // (a, b) = (high, low)
a = find(a); b = find(b);
if (a == b) return;
pr[b] = a;
}
void init(ll s) {
ll i;
for (i = 1; i <= n; i++) vis[i] = false;
}
void dfs(ll s) {
ll l;
vis[s] = true;
for (auto u : qdg[s]) {
if (!vis[u]) continue;
l = find(u);
dp[s]++; dp[u]++; dp[l] -= 2;
}
for (auto [u, w1, w2] : adj[s]) {
if (vis[u]) {
wu[s][0] = w1; wu[s][1] = w2; continue;
}
dfs(u);
onion(s, u);
}
}
void calc(ll s) {
vis[s] = true;
for (auto [u, w1, w2] : adj[s]) {
if (vis[u]) continue;
calc(u);
dp[s] += dp[u];
}
if (dp[s] == 0) return;
res += min(dp[s] * wu[s][0], wu[s][1]);
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
#if !ONLINE_JUDGE && !EVAL
ifstream cin("input.txt");
ofstream cout("output.txt");
#endif
cin >> n;
for (i = 1; i <= n - 1; i++) {
cin >> a >> b >> w1 >> w2;
adj[a].pb({b, w1, w2}); adj[b].pb({a, w1, w2});
}
for (i = 1; i <= n; i++) {
if (i != 1) qdg[i].pb(i - 1);
if (i != n) qdg[i].pb(i + 1);
}
for (i = 1; i <= n; i++) pr[i] = i;
dfs(1);
init(1);
calc(1);
/* for (i = 1; i <= n; i++) cout << dp[i] << ' ';
cout << nl; */
cout << res << nl;
return 0;
}
