#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 2e5 + 5;
vector<array<int, 3>> g[maxn];
int cost1[maxn], cost2[maxn], jump[maxn][20], h[maxn], cnt[maxn];
void dfs(int u, int p){
for(auto [v, w1, w2]: g[u]){
if(v == p) continue;
h[v] = h[u] + 1;
jump[v][0] = u;
cost1[v] = w1;
cost2[v] = w2;
dfs(v, u);
}
}
int LCA(int u , int v){
if(h[u] < h[v]) swap(u , v);
for(int i = 19; i >= 0; i--) if(h[jump[u][i]] >= h[v]) u = jump[u][i];
if(u == v) return u;
for(int i = 19; i >= 0; i--){
if(jump[u][i] != jump[v][i]) u = jump[u][i], v = jump[v][i];
}
return jump[u][0];
}
void add(int u , int p){
for(auto [v, trash, _]: g[u]){
if(v == p) continue;
add(v , u);
cnt[u] += cnt[v];
}
}
void solve(){
int n; cin >> n;
for(int i = 1; i < n; i++){
int u, v, w1, w2; cin >> u >> v >> w1 >> w2;
g[u].push_back({v, w1, w2});
g[v].push_back({u, w1, w2});
}
dfs(1, 1);
for(int j = 1; j < 20; j++){
for(int i = 1; i <= n; i++) jump[i][j] = jump[jump[i][j - 1]][j - 1];
}
for(int i = 1; i < n; i++){
cnt[i]++;
cnt[i + 1]++;
cnt[LCA(i, i + 1)] -= 2;
}
add(1, 1);
int ans = 0;
for(int i = 1; i <= n; i++) ans += min(cnt[i] * cost1[i], cost2[i]);
cout << ans;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
solve();
return 0;
}
