#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
using namespace std;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<pl> vpl;
typedef vector<ld> vld;
typedef pair<ld, ld> pld;
typedef vector<pi> vpi;
//typedef tree<ll, null_type, less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
template<typename T>
ostream &operator<<(ostream &os, vector<T> &a) {
os << "[";
for (int i = 0; i < ll(a.size()); i++) { os << a[i] << ((i != ll(a.size() - 1) ? " " : "")); }
os << "]\n";
return os;
}
#define all(x) x.begin(),x.end()
#define YES out("YES")
#define NO out("NO")
#define out(x){cout << x << "\n"; return;}
#define GLHF ios_base::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL)
#define print(x){for(auto ait:x) cout << ait << " "; cout << "\n";}
#define pb push_back
#define umap unordered_map
template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
is >> p.first >> p.second;
return is;
}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, pair<T1, T2> &p) {
os << "" << p.first << " " << p.second << "";
return os;
}
void usaco(string taskname) {
string fin = taskname + ".in";
string fout = taskname + ".out";
const char *FIN = fin.c_str();
const char *FOUT = fout.c_str();
freopen(FIN, "r", stdin);
freopen(FOUT, "w", stdout);
}
template<typename T>
void read(vector<T> &v) {
int n = v.size();
for (int i = 0; i < n; i++)
cin >> v[i];
}
template<typename T>
vector<T> UNQ(vector<T> a) {
vector<T> ans;
for (T t: a)
if (ans.empty() || t != ans.back())
ans.push_back(t);
return ans;
}
void solve();
int main() {
GLHF;
int t = 1;
//cin >> t;
while (t--)
solve();
}
vvi up,g;
vi dep,d;
void dfs(int src,int par){
if(par!=-1)
dep[src]=dep[par]+1;
up[src][0]=par;
for(int nbr:g[src])
if(nbr!=par)
dfs(nbr,src);
}
void dfs2(int src,int par){
for(int nbr:g[src])
if(nbr!=par)
dfs2(nbr,src),d[src]+=d[nbr];
}
int lg=20;
int lca(int u,int v){
if(u==v)return u;
if(dep[u]<dep[v])
swap(u,v);
for(int i=0; i<lg; i++)
if((dep[u]-dep[v])&(1<<i))
u=up[u][i];
if(u==v)return u;
for(int i=lg-1; 0<=i; i--)
if(up[u][i]!=up[v][i])
u=up[u][i],v=up[v][i];
if(u!=v)
u=up[u][0];
return u;
}
map<pl,ll>C1,C2;
void solve() {
int n;
cin >> n;
g.resize(n+1);
dep.resize(n+1);
up.resize(n+1,vi(lg,-1));
for(int i=0; i<n-1;i++){
ll u,v,c1,c2;
cin >> u >> v >> c1 >> c2;
g[u].pb(v);
g[v].pb(u);
C1[{u,v}]=C1[{v,u}]=c1;
C2[{u,v}]=C2[{v,u}]=c2;
}
ll ans=0;
dfs(1,-1);
for(int j=1; j<lg ; j ++)
for(int i=1; i<=n; i++)
if(up[i][j-1]!=-1)
up[i][j]=up[up[i][j-1]][j-1];
d.resize(n+1);
for(int i=1; i<n; i++){
int l=lca(i,i+1);
d[i]++,d[i+1]++;
d[l]-=2;
}
dfs2(1,-1);
for(int i=2; i<=n; i++){
ll t=d[i];
ll mn=min(t*C1[{i,up[i][0]}],
C2[{i,up[i][0]}] );
ans+=mn;
}
out(ans)
}
