#include <bits/stdc++.h>
using namespace std;
template <typename A, typename B>
string to_string(pair<A, B> p);
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
string to_string(const string& s) {
return '"' + s + '"';
}
string to_string(const char* s) {
return to_string((string) s);
}
string to_string(bool b) {
return (b ? "true" : "false");
}
string to_string(vector<bool> v) {
bool first = true;
string res = "{";
for (int i = 0; i < static_cast<int>(v.size()); i++) {
if (!first) {
res += ", ";
}
first = false;
res += to_string(v[i]);
}
res += "}";
return res;
}
template <size_t N>
string to_string(bitset<N> v) {
string res = "";
for (size_t i = 0; i < N; i++) {
res += static_cast<char>('0' + v[i]);
}
return res;
}
template <typename A>
string to_string(A v) {
bool first = true;
string res = "{";
for (const auto &x : v) {
if (!first) {
res += ", ";
}
first = false;
res += to_string(x);
}
res += "}";
return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << " " << to_string(H);
debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
const int MAX_N = 2e5 + 5;
const int MAX_K = 20 + 5;
vector<vector<tuple<int, int, int>>> g(MAX_N);
vector<vector<int>> dp(MAX_N, vector<int>(MAX_K, 0));
vector<int> sum(MAX_N), depth(MAX_N);
void dfs (int node = 0, int p = -1) {
dp[node][0] = p;
sum[node] = 0;
for (auto cur : g[node]) {
int to = get<0> (cur);
if (to != p) {
depth[to] = depth[node] + 1;
dfs (to, node);
}
}
}
int kth (int u, int d) {
for (int i = 0; i < MAX_K; i++) {
if ((d >> i) & 1) {
u = dp[u][i];
}
}
return u;
}
int lca (int u, int v) {
if (depth[u] < depth[v]) swap (u, v);
u = kth (u, depth[u] - depth[v]);
if (u == v) return u;
for (int i = MAX_K - 1; i >= 0; i--) {
if (dp[u][i] != dp[v][i]) {
u = dp[u][i];
v = dp[v][i];
}
}
return dp[u][0];
}
long long calc_sub (int node = 0, int p = -1) {
long long res = 0;
for (auto cur : g[node]) {
int to = get<0> (cur);
if (to != p) {
res += calc_sub (to, node);
sum[node] += sum[to];
}
}
for (auto cur : g[node]) {
int to = get<0> (cur);
if (to == p) continue;
int vezes = sum[to];
long long a = 1LL * vezes * get<1> (cur);
long long b = get<2> (cur);
res += min (a, b);
}
return res;
}
int main () {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
for (int i = 0; i < n - 1; i++) {
int st, et, one_time, mult_time;
cin >> st >> et >> one_time >> mult_time;
--st; --et;
g[st].emplace_back(make_tuple(et, one_time, mult_time));
g[et].emplace_back(make_tuple(st, one_time, mult_time));
}
dfs ();
for (int j = 1; j < MAX_K; j++) {
for (int i = 0; i < n; i++) {
if (~dp[i][j - 1]) {
dp[i][j] = dp[ dp[i][j - 1] ][j - 1];
}
}
}
for (int et = 1; et < n; et++) {
int st = et - 1;
++sum[st];
++sum[et];
sum[lca(st, et)] -= 2;
}
cout << calc_sub () << '\n';
return 0;
}
