#include<bits/stdc++.h>
using namespace std;
const int mx=15;
typedef long long ll;
int inf=1e9+10;
const int mod=1e9+7;
int n,m;
vector<pair<int,pair<ll,ll>>> adj[200002];
int dp[2000001][22];
int depth[mx];
void dfs(int node,int p){
dp[node][0]=p;
for(int i=1;i<=20;i++){
dp[node][i]=dp[dp[i][i-1]][i-1];
}
for(auto it:adj[node]){
if(it.first!=p){
depth[it.first]=depth[node]+1;
dfs(it.first,node);
}
}
return;
}
int kth(int node,int k){
for(int i=0;i<20;i++){
if((1<<i)&k){
// cout<<"TEST "<<i;
node=dp[node][i];
}
}
return node;
}
int lca(int a,int b){
if(depth[a]<depth[b]){
swap(a,b);
}
a=kth(a,depth[a]-depth[b]);
if(a==b){return a;}
for(int i=19;i<=0;i--){
int aa=dp[a][i];
int bb=dp[b][i];
if(aa==bb){
continue;
}else{
a=aa;b=bb;
}
}
return dp[a][0];
}
int dp2[200002];
ll ans;
int dfs2(int node,int p){
ll sum=dp2[node];
for(auto it:adj[node]){
if(it.first==p){continue;}
ll sum2=0;
sum2+=dfs2(it.first,node);
sum+=sum2;
ans+=min(1LL*it.second.first*sum2,it.second.second);
}
return sum;
}
int main(){
cin>>n;
for(int i=0;i<n-1;i++){
int x,y,c1,c2;
cin>>x>>y>>c1>>c2;
adj[x].push_back({y,{c1,c2}});
adj[y].push_back({x,{c1,c2}});
}
dfs(1,-1);
//cout<<lca(2,4);
for(int i=1;i<n;i++){
dp2[i]++;
dp2[i+1]++;
int x=lca(i,i+1);
dp2[x]-=2;
}
dfs2(1,-1);
cout<<ans;
}
