#include<bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = a; i < b; ++i)
#define REP(i, n) FOR(i, 0, n)
#define _ << " " <<
#define sz(x) ((int) x.size())
#define pb(x) push_back(x)
#define TRACE(x) cerr << #x << " = " << x << endl
typedef long long ll;
typedef pair<int, int> point;
const int mod = 1e9 + 7;
int add(int x, int y) {x += y; if(x >= mod) return x - mod; return x;}
int sub(int x, int y) {x -= y; if(x < 0) return x + mod; return x;}
int mul(int x, int y) {return (ll) x * y % mod;}
const int MAXN = 2e5 + 5, LOG = 19;
struct Edge{
int x = 0, cost1 = 0, cost2 = 0;
Edge(){}
Edge(int x, int cost1, int cost2) : x(x), cost1(cost1), cost2(cost2) {}
};
int n, anc[LOG][MAXN], dep[MAXN];
vector <Edge> E[MAXN];
Edge par[MAXN];
void dfs(int x, int p = -1){
for(auto e : E[x]){
if(e.x == p) continue;
dep[e.x] = dep[x] + 1;
anc[0][e.x] = x;
par[e.x] = e;
dfs(e.x, x);
}
}
int get_lca(int x, int y){
if(dep[x] < dep[y])
swap(x, y);
for(int i = LOG - 1; i >= 0; --i)
if( dep[x] - (1 << i) >= dep[y] )
x = anc[i][x];
if(x == y) return x;
for(int i = LOG - 1; i >= 0; --i)
if( anc[i][x] != anc[i][y] ){
x = anc[i][x];
y = anc[i][y];
}
return anc[0][x];
}
ll extra[MAXN], sum[MAXN], after[MAXN];
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n;
REP(i, n - 1){
int a, b, cost1, cost2; cin >> a >> b >> cost1 >> cost2;
a --; b --;
E[a].pb(Edge(b, cost1, cost2));
E[b].pb(Edge(a, cost1, cost2));
}
dfs(0);
FOR(i, 1, LOG) REP(j, n){
int x = anc[i - 1][j];
anc[i][j] = anc[i - 1][x];
}
FOR(i, 1, n){
int x = i, y = i - 1;
if(dep[x] > dep[y])
swap(x, y);
int lca = get_lca(x, y);
if(lca != x && lca != y){
extra[x] ++; extra[y] ++;
extra[lca] -= 2;
}
else if(lca == x){
extra[y] ++;
extra[lca] --;
}
else
assert(n == 0);
}
vector <point> v;
FOR(i, 1, n)
v.pb(point( dep[i], i ));
sort(v.rbegin(), v.rend());
ll sol = 0;
for(int i = 0; i < n - 1; ++i){
int x = v[i].second;
extra[anc[0][x]] += extra[x];
ll add1 = (ll)par[x].cost1 * (ll)extra[x];
ll add2 = (ll)par[x].cost2;
sol += min(add1, add2);
}
cout << sol;
}
