#include <bits/stdc++.h>
const int N = 2e5;
const int M = 2e5;
const int LOG = 20;
#define ll long long
const ll MOD = 5e6;
const ll INF = 1e9;
#define fi first
#define se second
using namespace std;
int n;
ll h[N+3], dp[N+3];
ll up[N+3][LOG+3];
vector<int> v[N+3];
ll ans = 0;
struct node{
ll x, y, z, check;
};
vector<node> t[N+3];
void dfs(ll t){
for(auto res : v[t]){
if(res == up[t][0])continue;
up[res][0] = t;
h[res] = h[t] + 1;
for(int i=1;i<=LOG;i++){
up[res][i] = up[up[res][i-1]][i-1];
}
dfs(res);
}
}
ll LCA(ll u, ll v){
if(h[u] != h[v]){
if(h[u] < h[v])swap(u, v);
ll res = h[u] - h[v];
for(int i=0;(1 << i) <= res;i++){
if(res >> i & 1)u = up[u][i];
}
}
if(u == v)return u;
for(int i=__lg(h[u]);i>=0;i--){
if(up[u][i] != up[v][i]){
u = up[u][i], v = up[v][i];
}
}
return up[u][0];
}
void dfs2(ll t, ll p){
for(auto res : v[t]){
if(res == p)continue;
dfs2(res, t);
dp[t] += dp[res];
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
// freopen("main.inp","r",stdin);
// freopen("main.out","w",stdout);
cin>>n;
for(int i=1;i<n;i++){
int x, y, a, b; cin>>x>>y>>a>>b;
v[x].push_back(y);
v[y].push_back(x);
t[x].push_back({y, a, b});
}
dfs(1);
for(int i=1;i<=n-1;i++){
int lca = LCA(i, i+1);
dp[i]++, dp[i+1]++;
dp[lca]-=2;
}
dfs2(1, 0);
for(int i=1;i<=n;i++){
for(auto res : t[i]){
int par;
if(h[res.x] > h[i])par = res.x;
else par = i;
ll val = min(dp[par]*res.y, res.z);
ans += val;
}
}
cout<<ans<<"\n";
return 0;
}
