#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
static int cnt = 0;
int n, head[N], pos[N], h[N], par[20][N], subt[N];
vector <pair <int, pair <int, int> > > g[N];
pair <int, int> val[N];
struct SegmentTree {
long long node[N << 2];
int lazy[N << 2];
void init (int i, int l, int r) {
if (l == r) {
node[i] = lazy[i] = 0;
return;
}
int mid = l + r >> 1;
init(i << 1, l, mid);
init(i << 1 | 1, mid + 1, r);
node[i] = 0;
lazy[i] = 0;
}
void dolazy (int i, int l, int r) {
if (lazy[i]) {
node[i] += 1LL * lazy[i] * (r - l + 1);
if (l != r) {
lazy[i << 1] += lazy[i];
lazy[i << 1 | 1] += lazy[i];
}
lazy[i] = 0;
}
}
void update (int i, int l, int r, int a, int b, int val) {
dolazy(i, l, r);
if (l > r || a > r || b < l) return;
if (a <= l && r <= b) {
node[i] += 1LL * val * (r - l + 1);
if (l != r) {
lazy[i << 1] += val;
lazy[i << 1 | 1] += val;
}
return;
}
int mid = l + r >> 1;
update(i << 1, l, mid, a, b, val);
update(i << 1 | 1, mid + 1, r, a, b, val);
node[i] = node[i << 1] + node[i << 1 | 1];
}
long long query (int i, int l, int r, int a, int b) {
if (l > r || a > r || b < l) return 0;
dolazy(i, l, r);
if (a <= l && r <= b) return node[i];
int mid = l + r >> 1;
return query(i << 1, l, mid, a, b) + query(i << 1 | 1, mid + 1, r, a, b);
}
} it;
void dfs (int u, int p) {
subt[u] = 1;
for (auto V: g[u]) {
int v = V.first, c1 = V.second.first, c2 = V.second.second;
if (v == p) continue;
h[v] = h[u] + 1;
par[0][v] = u;
val[v] = {c1, c2};
dfs(v, u);
subt[u] += subt[v];
}
}
void makeLCA(){
for (int i = 1; i < 20; i++) {
for (int j = 1; j <= n; j++) {
if (par[i - 1][j] != -1) {
par[i][j] = par[i - 1][par[i - 1][j]];
}
}
}
}
int LCA (int x, int y) {
if (h[x] > h[y]) swap(x, y);
for (int i = 19; i >= 0; i--) {
if (par[i][y] != -1 && h[y] - (1 << i) >= h[x]) {
y = par[i][y];
}
}
if (x == y) return x;
for (int i = 19; i >= 0; i--) {
if (par[i][x] != -1 && par[i][y] != -1 && par[i][x] != par[i][y]) {
x = par[i][x];
y = par[i][y];
}
}
if (x == y) return x;
return par[0][x];
}
void HLD (int u, int p) {
if (!head[u]) head[u] = u;
pos[u] = ++cnt;
int big = -1;
for (auto V: g[u]) {
int v = V.first;
if (v == p) continue;
if (big == -1 || subt[big] < subt[v]) big = v;
}
if (big != -1) {
head[big] = head[u];
HLD(big, u);
}
for (auto V: g[u]) {
int v = V.first;
if (v == p || v == big) continue;
HLD(v, u);
}
}
void augment_path (int u, int v) {
int p = LCA(u, v);
while (head[u] != head[p]) {
it.update(1, 1, cnt, pos[head[u]], pos[u], 1);
u = par[0][head[u]];
}
while (head[v] != head[p]) {
it.update(1, 1, cnt, pos[head[v]], pos[v], 1);
v = par[0][head[v]];
}
it.update(1, 1, cnt, pos[p], pos[u], 1);
it.update(1, 1, cnt, pos[p], pos[v], 1);
it.update(1, 1, cnt, pos[p], pos[p], -2);
}
int main(){
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n; memset(par, -1, sizeof(par));
for (int i = 1; i <= n - 1; i++) {
int u, v, c1, c2;
cin >> u >> v >> c1 >> c2;
g[u].push_back({v, {c1, c2}});
g[v].push_back({u, {c1, c2}});
}
dfs(1, 1);
makeLCA();
HLD(1, 1);
it.init(1, 1, cnt);
for (int i = 1; i < n; i++) augment_path(i, i + 1);
long long ans = 0;
for (int i = 1; i <= n; i++) ans += min(1LL * val[i].first * it.query(1, 1, cnt, pos[i], pos[i]), (long long)val[i].second);
cout << ans;
return 0;
}
