#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int inf = 1e9 + 7;
const ll infll = 1e18;
template<typename T>
istream &operator>>(istream &is, vector<T> &a) {
for (auto &i : a) {
is >> i;
}
return is;
}
struct BinaryJumps {
static const int lg = 18;
vector<int> d;
vector<vector<int>> up;
BinaryJumps() {}
BinaryJumps(int n) {
d.resize(n);
up.resize(lg, vector<int>(n, -1));
}
void add_leaf(int v, int p) {
d[v] = d[p] + 1;
up[0][v] = p;
for (int i = 1; i < lg; ++i) {
if (up[i - 1][v] != -1) {
up[i][v] = up[i - 1][up[i - 1][v]];
}
}
}
int la(int v, int k) {
for (int i = lg - 1; i >= 0; --i) {
if (k >= (1 << i)) {
k -= (1 << i);
v = up[i][v];
}
}
return v;
}
int lca(int u, int v) {
if (d[u] < d[v]) {
swap(u, v);
}
u = la(u, d[u] - d[v]);
for (int i = lg - 1; i >= 0; --i) {
if (up[i][u] != up[i][v]) {
u = up[i][u];
v = up[i][v];
}
}
if (u == v) {
return u;
}
return up[0][u];
}
};
vector<vector<array<int, 3>>> g;
BinaryJumps tr;
vector<int> dp;
ll ans = 0;
void dfs1(int v, int p = -1) {
for (auto [u, c1, c2] : g[v]) {
if (u != p) {
tr.add_leaf(u, v);
dfs1(u, v);
}
}
}
void dfs2(int v, int p = -1) {
for (auto [u, c1, c2] : g[v]) {
if (u != p) {
dfs2(u, v);
dp[v] += dp[u];
ans += min(c1 * 1ll * dp[u], ll(c2));
}
}
}
int32_t main() {
#ifdef LOCAL
freopen("/tmp/input.txt", "r", stdin);
#else
ios::sync_with_stdio(false);
cin.tie(nullptr);
#endif
int n;
cin >> n;
g.resize(n);
for (int i = 1; i < n; ++i) {
int u, v, c1, c2;
cin >> u >> v >> c1 >> c2;
--u;
--v;
g[u].push_back({v, c1, c2});
g[v].push_back({u, c1, c2});
}
tr = BinaryJumps(n);
dfs1(0);
dp.resize(n);
for (int i = 0; i + 1 < n; ++i) {
int u = i;
int v = i + 1;
int w = tr.lca(u, v);
dp[u] += 1;
dp[v] += 1;
dp[w] -= 2;
}
dfs2(0);
cout << ans << "\n";
return 0;
}
