#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define fi first
#define se second
#define pb push_back
#define pii pair<int,int>
#define pll pair<long long,long long>
using namespace std;
struct nd{
vector<ll> ady;
}T[200010];
ll n,u,v,a,b,d[200010],f[200010][20],sum[200010],ans;
map< pll , pll > c;
void dfs(ll node,ll ant,ll dist){
d[ node ] = dist;
f[ node ][ 0 ] = ant;
for(auto sig:T[node].ady){
if( sig==ant ) continue;
dfs( sig , node , dist+1 );
}
return;
}
ll lca( ll A , ll B ){
if( d[ A ] < d[ B ] ) swap( A , B );
for(int i=19; i>=0; i--) if( d[A]-(1LL<<i) >= d[ B ] ){
A = f[ A ][ i ];
}
if( A==B ) return B;
for(int i=19; i>=0; i--){
if( f[A][i]!=f[B][i] ){
A = f[A][i];
B = f[B][i];
}
}
return f[A][0];
}
void compute(ll node, ll ant){
for(auto sig:T[node].ady){
if( sig == ant ) continue;
compute( sig , node );
sum[node]+=sum[sig];
}
if( node!=1 ) ans+=min( sum[node]*c[ { node , ant } ].fi , c[ { node , ant } ].se );
return;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
for(int i=1; i<n; i++){
cin >> u >> v >> a >> b;
c[ {u,v} ] = c[ {v,u} ] = {a,b};
T[u].ady.pb( v );
T[v].ady.pb( u );
}
dfs( 1 , 1 , 0 );
for(int pot=1; pot<20; pot++) for(int i=1; i<=n; i++) f[i][pot] = f[ f[i][pot-1] ][ pot-1 ];
for(int i=1; i<n; i++){
sum[i]++;
sum[i+1]++;
sum[ lca( i , i+1 ) ]-=2;
}
compute( 1 , 1 );
cout << ans;
return 0;
}
