#pragma GCC optimize("Ofast,unroll-loops,inline")
#pragma GCC target("avx2,bmi,bmi2")
#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define pb push_back
#define prec fixed<<setprecision
#define endl '\n'
#define all(x) x.begin(),x.end()
#define pll pair<ll,ll>
#define open(name) if(fopen(name".inp", "r")){freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);}
using namespace std;
const int maxN=1e5+69;
const int mod=998244353;
ll n,f[maxN],c[2][maxN],tin[maxN],tout[maxN],timer=0,up[maxN][20];
struct edg{ll v,w,z;};
vector<edg> adj[maxN];
void dfs(int v, int p)
{
tin[v] = ++timer;
up[v][0] = p;
for (int i = 1; i < 20; ++i)
up[v][i] = up[up[v][i-1]][i-1];
for (auto [u,w,z] : adj[v]) {
if (u != p){
dfs(u, v);
c[0][u]=w;
c[1][u]=z;
}
}
tout[v] = ++timer;
}
bool is_ancestor(int u, int v)
{
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca(int u, int v)
{
if (is_ancestor(u, v))
return u;
if (is_ancestor(v, u))
return v;
for (int i = 19; i >= 0; --i) {
if (!is_ancestor(up[u][i], v))
u = up[u][i];
}
return up[u][0];
}
ll pfs[maxN];
void dfss(ll u,ll p=0){
for(auto [v,_,__]:adj[u]){
if(v==p)continue;
dfss(v,u);
pfs[u]+=pfs[v];
}
}
void Enter(){
cin>>n;
for(int i=1;i<n;i++){
ll u,v,w,c;cin>>u>>v>>w>>c;
adj[u].pb({v,w,c});
adj[v].pb({u,w,c});
}
dfs(1,0);
for(int i=1;i<n;i++){
ll x=lca(i,i+1);
pfs[i]++;
pfs[i+1]++;
pfs[x]-=2;
}
dfss(1);
ll r=0;
for(int i=2;i<=n;i++)r+=min(pfs[i]*c[0][i],c[1][i]);
cout<<r;
}
signed main(){
//open("zzz");
cin.tie(nullptr);ios_base::sync_with_stdio(NULL);
//ll t=1;cin>>t;while(t--)
Enter();
}
