#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, U b) {
  if (a < b) a = b;
}
template <typename T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <typename T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <typename T>
inline void println(T first) {
  print(first), putchar('\n');
}
template <typename T>
inline void printsp(T first) {
  print(first), putchar(' ');
}
template <class T, class T1>
inline void print(T first, T1 second) {
  printsp(first), println(second);
}
template <class T, class T1, class T2>
inline void print(T first, T1 second, T2 z) {
  printsp(first), printsp(second), println(z);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a % m)
    if (b & 1) ans = 1LL * ans * a % m;
  return ans;
}
vector<pair<int, int> > adj[3030];
int cnt, mx;
void dfs(int u, int fa = 0, int tot = 0, int mn = 0) {
  smin(mn, tot);
  smax(mx, tot - mn);
  for (int i = 0; i < adj[u].size(); i++) {
    int v = adj[u][i].first;
    if (v == fa) continue;
    cnt += adj[u][i].second;
    dfs(v, u, tot + (adj[u][i].second ? 1 : -1), mn);
  }
}
int main() {
  int n;
  gn(n);
  for (int i = 1, u, v; i < n; i++) {
    gn(u, v);
    adj[u].push_back(pair<int, int>(v, 0));
    adj[v].push_back(pair<int, int>(u, 1));
  }
  int ans = 0x3f3f3f3f;
  for (int i = 1; i <= n; i++) {
    cnt = 0;
    mx = 0;
    dfs(i);
    smin(ans, cnt - mx);
  }
  println(ans);
  return 0;
}
