#include<bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define int long long
using namespace std;
const int N=1e6,M=2e3,mod=1e9+7;
int n,up[N][30],innode[N],outnode[N],timee=0,val[N],val2[N];
map<pair<int,int>,int>mpp;
vector<int>adj[N];
vector<pair<int,int>>v;
void dfs(int node,int par){
innode[node]=timee++;
up[node][0]=par;
for(int j=1;j<ceil(log2(n));j++)
up[node][j]=up[up[node][j-1]][j-1];
for(auto x:adj[node]){
if(x==par)
continue;
dfs(x,node);
}
outnode[node]=timee++;
}
bool is_parent(int x,int y){
return innode[x]<=innode[y]&&outnode[x]>=outnode[y];
}
int lca(int x,int y){
if(is_parent(x,y))
return x;
if(is_parent(y,x))
return y;
for(int i=ceil(log2(n));i>=0;i--){
if(!is_parent(up[x][i],y))
x=up[x][i];
}
return up[x][0];
}
void dfs2(int node,int par){
for(auto x:adj[node]){
if(x==par)
continue;
dfs2(x,node);
val2[node]+=val2[x];
mpp[{node,x}]=val2[x];
mpp[{x,node}]=val2[x];
}
val2[node]+=val[node];
}
main()
{
int n;
cin>>n;
map<pair<int,int>,pair<int,int>>mp;
for(int i=0;i<n-1;i++){
int x,y,cost1,cost2;
cin>>x>>y>>cost1>>cost2;
v.pb({x,y});
mp[{x,y}]={cost1,cost2};
adj[x].pb(y);
adj[y].pb(x);
}
dfs(1,0);
innode[0]=-1;
outnode[0]=++timee;
for(int i=2;i<=n;i++){
int lcaa=lca(i,i-1);
val[i]++;
val[i-1]++;
val[lcaa]-=2;
}
dfs2(1,0);
int ans=0;
for(int i=0;i<v.size();i++){
int cost1=mp[{v[i].F,v[i].S}].F*mpp[{v[i].F,v[i].S}];
int cost2=mp[{v[i].F,v[i].S}].S;
ans+=min(cost1,cost2);
}
cout<<ans<<endl;
return 0;
}
