#include <algorithm>
#include <cassert>
#include <cctype>
#include <chrono>
#define _USE_MATH_DEFINES
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <tuple>
#include <vector>
using namespace std;

#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;
const int MOD = 1000000007; // 998244353
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
/*-------------------------------------------------*/
using CostType = long long;
struct Edge {
  int src, dst;
  CostType cost;
  Edge(int src_, int dst_, CostType cost_ = 0) : src(src_), dst(dst_), cost(cost_) {}
  inline bool operator<(const Edge &rhs) const {
    return cost != rhs.cost ? cost < rhs.cost : dst != rhs.dst ? dst < rhs.dst : src < rhs.src;
  }
  inline bool operator<=(const Edge &rhs) const { return cost <= rhs.cost; }
  inline bool operator>(const Edge &rhs) const {
    return cost != rhs.cost ? cost > rhs.cost : dst != rhs.dst ? dst > rhs.dst : src > rhs.src;
  }
  inline bool operator>=(const Edge &rhs) const { return cost >= rhs.cost; }
};

struct DoubleSweep {
  using Pci = pair<CostType, int>;

  int s, t;
  CostType diameter;

  DoubleSweep(const vector<vector<Edge> > &graph_) : graph(graph_) {
    Pci tmp1 = dfs(-1, 0);
    s = tmp1.second;
    Pci tmp2 = dfs(-1, tmp1.second);
    t = tmp2.second;
    diameter = tmp2.first;
  }

private:
  vector<vector<Edge> > graph;

  Pci dfs(int par, int ver) {
    Pci res = {0, ver};
    for (Edge e : graph[ver]) if (e.dst != par) {
      Pci result = dfs(ver, e.dst);
      result.first += e.cost;
      if (result.first > res.first) res = result;
    }
    return res;
  }
};

int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  // freopen("input.txt", "r", stdin);

  int n; cin >> n;
  vector<vector<Edge> > graph(n);
  REP(i, n - 1) {
    int a, b; cin >> a >> b; --a; --b;
    graph[a].emplace_back(Edge(a, b, 1));
    graph[b].emplace_back(Edge(b, a, 1));
  }
  DoubleSweep ds(graph);
  cout << n - 1 - ds.diameter << '\n';
  return 0;
}