#include<bits/stdc++.h>
#define lcm(a,b) (a/__gcd(a,b))*b
#define fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ll long long int
#define vi vector<int>
#define vll vector<ll>
#define pb push_back
#define F first
#define S second
#define mp make_pair
//salida rapida "\n"
//DECIMALES fixed<<sp(n)<<x<<endl;
//gcd(a,b)= ax + by
//lCB x&-x
//set.erase(it) - ersases the element present at the required index//auto it = s.find(element)
//set.find(element) - iterator pointing to the given element if it is present else return pointer pointing to set.end()
//set.lower_bound(element) - iterator pointing to element greater than or equal to the given element
//set.upper_bound(element) - iterator pointing to element greater than the given element
// | ^
using namespace std;
vector<vector<int> >G;
map<pair<int,int>,pair<int,int> >m;
map<pair<int,int>, int >cant;
vi dp;
void dfs(int u, int final){
if(u==final){
return;
}
for(auto it : G[u]){
if(dp[it]==-1){
dp[it]=u;
dfs(it,final);
}
}
}
int main()
{
int n,a,b,c1,c2;
cin>>n;
G.assign(n+1,vi());
for(int i=1;i<n;i++){
cin>>a>>b>>c1>>c2;
G[a].pb(b);
G[b].pb(a);
m[{a,b}]={c1,c2};
}
for(int i=2;i<=n;i++){
dp.assign(n+1,-1);
dp[i-1]=i-1;
dfs(i-1,i);
int pos=i;
while(1){
if(dp[pos]==pos){
break;
}
int a=pos,b=dp[pos];
if(b<a)swap(a,b);
cant[{a,b}]++;
pos=dp[pos];
}
}
ll res=0;
for(auto it : cant){
int c=it.S;
//veces que pasa por el camino
pair<int,int>a=it.F;
if(m[a].F*c<m[a].S){
res+=m[a].F*c;
}else{
res+=m[a].S;
}
}
cout<<res<<endl;
return 0;
}
