#include <bits/stdc++.h>
#define ll long long
#define ff first
#define ss second
#define mp(x,y) make_pair((x),(y))
#define bit(x,i) (((x)>>(i))&1)
#define MASK(i) (1<<(i))
#define randomize mt19937_64 mt(chrono::steady_clock::now().time_since_epoch().count())
using namespace std;
const int maxn=2e5+5;
const ll oo=2e18+5;
const int MOD=1e9+7;
const int inf=1e9+7;
void init()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
}
int n,c[2][maxn],pa[maxn][20],depth[maxn];
vector< pair<int,int> > adj[maxn];
void dfs(int u,int pre)
{
for(int it=0;it<(int)adj[u].size();it++)
{
int v=adj[u][it].ff;
if(v==pre) continue;
depth[v]=depth[u]+1;
pa[v][0]=u;
for(int j=1;j<=18;j++) pa[v][j]=pa[pa[v][j-1]][j-1];
dfs(v,u);
}
}
int LCA(int u,int v)
{
if(depth[u]<depth[v]) swap(u,v);
for(int j=18;j>=0;j--) if(depth[u]-MASK(j)>=depth[v]) u=pa[u][j];
if(u==v) return u;
for(int j=18;j>=0;j--) if(pa[u][j]!=pa[v][j])
{
u=pa[u][j];
v=pa[v][j];
}
return pa[u][0];
}
ll cnt[maxn],sum[maxn];
void calc(int u,int pre,int id)
{
for(int it=0;it<(int)adj[u].size();it++)
{
int v=adj[u][it].ff,newId=adj[u][it].ss;
if(v==pre) continue;
calc(v,u,newId);
cnt[u]+=cnt[v];
}
if(id) sum[id]=cnt[u];
}
void solve()
{
cin>>n;
for(int i=1;i<n;i++)
{
int u,v;
cin>>u>>v>>c[0][i]>>c[1][i];
adj[u].push_back(mp(v,i));
adj[v].push_back(mp(u,i));
}
dfs(1,0);
for(int i=1;i<n;i++)
{
int w=LCA(i,i+1);
cnt[i]++;
cnt[i+1]++;
cnt[w]-=2;
}
calc(1,0,0);
ll ans=0;
for(int i=1;i<n;i++)
ans+=min(1LL*c[0][i]*sum[i],1LL*c[1][i]);
cout<<ans;
}
int main()
{
init();
// int t;
// cin>>t;
// while(t--)
solve();
return 0;
}
