/* -*- coding: utf-8 -*-
 *
 * 1484.cc:  No.1484 木に数を書き込む問題 / Just Write Numbers! 2 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

typedef vector<int> vi;
typedef queue<int> qi;

/* global variables */

vi nbrs[MAX_N];
int ds[MAX_N];

/* subroutines */

int bfs(int st) {
  memset(ds, -1, sizeof(ds));
  ds[st] = 0;
  qi q;
  q.push(st);

  int maxd = -1, gl = -1;
  while (! q.empty()) {
    int u = q.front(); q.pop();
    if (maxd < ds[u]) maxd = ds[u], gl = u;

    vi &nbru = nbrs[u];
    for (vi::iterator vit = nbru.begin(); vit != nbru.end(); vit++) {
      int v = *vit;
      if (ds[v] < 0) {
	ds[v] = ds[u] + 1;
	q.push(v);
      }
    }
  }

  return gl;
}

/* main */

int main() {
  int n;
  scanf("%d", &n);

  for (int i = 1; i < n; i++) {
    int a, b;
    scanf("%d%d", &a, &b);
    a--, b--;
    nbrs[a].push_back(b);
    nbrs[b].push_back(a);
  }

  int x = bfs(0);
  int y = bfs(x);

  printf("%d\n", 2 * (n - 1) - ds[y]);
  return 0;
}