#include <stdio.h>
#include <stdlib.h>
#define N 200000
long long min(long long a, long long b) { return a < b ? a : b; }
int ij[N - 1], aa[N - 1], bb[N - 1];
int *eh[N], eo[N];
void append(int i, int j) {
int o = eo[i]++;
if (o >= 2 && (o & o - 1) == 0)
eh[i] = (int *) realloc(eh[i], o * 2 * sizeof *eh[i]);
eh[i][o] = j;
}
int pp[N], qq[N], dd[N];
int dfs1(int p, int i, int d) {
int o, j_, s, k_;
pp[i] = p, dd[i] = d;
s = 1, k_ = 0, j_ = -1;
for (o = eo[i]; o--; ) {
int h = eh[i][o], j = i ^ ij[h];
if (j != p) {
int k = dfs1(i, j, d + 1);
if (k_ < k)
k_ = k, j_ = j;
s += k;
}
}
qq[i] = j_;
return s;
}
void dfs2(int p, int i, int q) {
int o, j_;
j_ = qq[i], qq[i] = q;
for (o = eo[i]; o--; ) {
int h = eh[i][o], j = i ^ ij[h];
if (j != p) {
dfs2(i, j, j == j_ ? q : j);
}
}
}
int lca(int i, int j) {
while (qq[i] != qq[j])
if (dd[qq[i]] > dd[qq[j]])
i = pp[qq[i]];
else
j = pp[qq[j]];
return dd[i] < dd[j] ? i : j;
}
int kk[N]; long long ans;
void dfs3(int p, int i) {
int o;
for (o = eo[i]; o--; ) {
int h = eh[i][o], j = i ^ ij[h];
if (j != p) {
dfs3(i, j);
ans += min(aa[h] * kk[j], bb[h]);
kk[i] += kk[j];
}
}
}
int main() {
int n, h, i, j;
scanf("%d", &n);
for (i = 0; i < n; i++)
eh[i] = (int *) malloc(2 * sizeof *eh[i]);
for (h = 0; h < n - 1; h++) {
scanf("%d%d%d%d", &i, &j, &aa[h], &bb[h]), i--, j--;
ij[h] = i ^ j;
append(i, h), append(j, h);
}
dfs1(-1, 0, 0);
dfs2(-1, 0, 0);
for (i = 0; i + 1 < n; i++)
kk[i]++, kk[i + 1]++, kk[lca(i, i + 1)] -= 2;
dfs3(-1, 0);
printf("%lld\n", ans);
return 0;
}
