#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#warning Check Integer OverFlow
#define ll long long
#define rep(i,a,b) for(int i=a;i<b;i++)
#define per(i,a,b) for(int i=a;i>=b;i--)
#define trav(a,b) for(auto a:b)
#define sz(a) a.size()
#define maxs(a,b) if(b>a)a=b
#define mins(a,b) if(b<a)a=b
#ifdef LOCAL
#define dbg(x) cerr<<"["<<#x<<":"<<x<<"] "
#define dbg2(a,b) dbg(a);dbg(b)
#define dbg3(a,b,c) dbg2(a,b);dbg(c)
#define dln cerr << ln
#else
#define dbg(x) 0
#define dbg2(a,b) 0
#define dbg3(a,b,c) 0
#define dln 0
#endif
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) (((a)/(__gcd(a,b))) * b)
#define print(arr) for(auto it = arr.begin();it < arr.end();it ++){cout << *it << " ";}cout << ln;
#define all(a) (a).begin(), (a).end()
#define vi vector<int>
#define v vector
#define p pair
#define pii p<int,int>
#define pb push_back
#define mk make_pair
#define f first
#define s second
#define ln "\n"
#define size siz
typedef long double ld;
using namespace std;
using namespace __gnu_pbds;
ll modF=1e9+7;
template<class T> using iset = tree<
T,
null_type,
less<T>,
rb_tree_tag,
tree_order_statistics_node_update>;
/*OUTPUT
*/
int n,timer;
vector<int> adj[2000];
int en[2000];
int pr[2000];
int size[2000];
int vis[2000];
map<int,map<int,int>> fr;
map<int,map<int,pii>> cost;
int dfs(int x,int par = -1){
if(vis[x])return 0;
vis[x] = 1;
en[timer] = x;
size[x] = 1;
pr[x] = par;
timer ++;
for(auto e:adj[x]){
size[x] += dfs(e,x);
}
return size[x];
}
bool fn(int i,int j){
if(fr.find(i) == fr.end())return false;
if(fr[i].find(j) == fr[i].end())return false;
return true;
}
void solve(){
cin >> n;
rep(i,0,n - 1){
int x,y,c1,c2;
cin >> x >> y >> c1 >> c2;
x --;y --;
adj[x].pb(y);
adj[y].pb(x);
fr[x][y] = 0;
cost[x][y] = mk(c1,c2);
}
dfs(0);
ll ans = 0;
for(int i = 1;i < n;i ++){
set<int> q;
for(int j = i;j < i + size[en[i]];j ++){
q.insert(en[j]);
}
int crr = en[i];
int prev = pr[en[i]];
if(!fn(crr,prev)){
swap(crr,prev);
}
for(auto e:q){
if(e != 0){
if(q.find(e - 1) == q.end()){
fr[crr][prev] ++;
}
}
if(e != n - 1){
if(q.find(e + 1) == q.end()){
fr[crr][prev] ++;
}
}
}
// dbg(n);
dbg(en[i]);
dbg2(i,fr[crr][prev]);
dln;
}
for(auto e:fr){
for(auto ed:e.s){
dbg2(e.f,ed.f);
dbg2(cost[e.f][ed.f].f,cost[e.f][ed.f].s);
dbg(fr[e.f][ed.f]);
dln;
if(cost[e.f][ed.f].f * fr[e.f][ed.f] < cost[e.f][ed.f].s){
ans += cost[e.f][ed.f].f * fr[e.f][ed.f];
}
else{
ans += cost[e.f][ed.f].s;
}
}
}
cout << ans << ln;
}
int main(){
ios::sync_with_stdio(0);cin.tie(0);
int t = 1;
// cin >> t;
while(t --){
solve();
}
}
