#include <bits/stdc++.h>
using namespace std;
const int N = 3010;
struct edge {
  int v, next, flag;
} e[N << 2];
int head[N], cnt;
void addedge(int u, int v, int flag) {
  e[cnt].v = v;
  e[cnt].flag = flag;
  e[cnt].next = head[u];
  head[u] = cnt++;
}
int sum[N], dp[N];
void dfs(int u, int pre) {
  sum[u] = 0;
  for (int i = head[u]; i != -1; i = e[i].next) {
    if (e[i].v == pre) continue;
    dfs(e[i].v, u);
    int v = e[i].v;
    sum[u] += sum[v] + e[i].flag;
  }
  dp[u] = sum[u];
  for (int i = head[u]; i != -1; i = e[i].next) {
    if (e[i].v == pre) continue;
    int v = e[i].v;
    dp[u] = min(dp[u], sum[u] - sum[v] + 1 - e[i].flag + dp[v] - e[i].flag);
  }
}
int main() {
  memset(head, -1, sizeof(head));
  int n;
  scanf("%d", &n);
  for (int i = 1; i < n; i++) {
    int x, y, z;
    scanf("%d%d", &x, &y);
    addedge(x, y, 0);
    addedge(y, x, 1);
  }
  int ans = 0x7fffffff;
  for (int i = 1; i <= n; i++) {
    dfs(i, -1);
    for (int j = 1; j <= n; j++) {
      ans = min(ans, sum[i] - sum[j] + dp[j]);
    }
  }
  printf("%d\n", ans);
  return 0;
}
