/*
ID: varunra2
LANG: C++
TASK: putovanje
*/
#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif
#define int long long
#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second
const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions
int n;
VVI adj;
struct lca {
VVI bin;
const int bits = 20;
VI tin, tout;
int timer = 0;
void dfs(int u, int v) {
tin[u] = timer++;
bin[u][0] = v;
for (int i = 1; i < bits; i++) {
int to = bin[u][i - 1];
if (to != -1)
bin[u][i] = bin[to][i - 1];
else
bin[u][i] = -1;
}
for (auto& x : adj[u]) {
if (x == v) continue;
dfs(x, u);
}
tout[u] = timer++;
}
void init() {
bin.resize(n);
trav(x, bin) x.resize(bits);
tin.resize(n);
tout.resize(n);
dfs(0, -1);
}
bool isAnc(int u, int v) {
if (u == -1) return true;
if (v == -1) return false;
return tin[u] <= tin[v] and tout[u] >= tout[v];
}
int getLCA(int u, int v) {
if (isAnc(u, v)) return u;
if (isAnc(v, u)) return v;
for (int i = bits - 1; i >= 0; i--) {
if (!isAnc(bin[u][i], v)) u = bin[u][i];
}
return bin[u][0];
}
bool isPar(int u, int v) {
if (bin[u][0] == v) return true;
return false;
}
} lc;
VI pref;
VVI edgs;
void init() {
pref.resize(n);
adj.resize(n);
edgs.resize(n - 1);
trav(x, edgs) x.resize(4);
}
void dfspref(int u, int v) {
for (auto& x : adj[u]) {
if (x == v) continue;
dfspref(x, u);
pref[u] += pref[x];
}
}
int32_t main() {
// #ifndef ONLINE_JUDGE
// freopen("putovanje.in", "r", stdin);
// freopen("putovanje.out", "w", stdout);
// #endif
cin.sync_with_stdio(0);
cin.tie(0);
cin >> n;
init();
for (int i = 0; i < n - 1; i++) {
int u, v, c1, c2;
cin >> u >> v;
u--, v--;
adj[u].PB(v);
adj[v].PB(u);
cin >> c1 >> c2;
edgs[i] = {u, v, c1, c2};
}
lc.init();
for (int i = 0; i < n - 1; i++) {
int u = i;
int v = i + 1;
int w = lc.getLCA(u, v);
pref[u]++;
pref[v]++;
pref[w] -= 2;
}
dfspref(0, -1);
int ret = 0;
for (int i = 0; i < n - 1; i++) {
int u = edgs[i][0];
int v = edgs[i][1];
if (!lc.isPar(u, v)) swap(u, v);
// par of u is v
int cnt, cost1, cost2;
cnt = pref[u];
cost1 = edgs[i][2];
cost2 = edgs[i][3];
ret += min(cnt * cost1, cost2);
}
cout << ret << '\n';
return 0;
}
