/* -*- coding: utf-8 -*-
 *
 * 1752.cc:  No.1752 Up-Down Tree - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 100000;

/* typedef */

typedef vector<int> vi;

/* global variables */

vi nbrs[MAX_N];
int ps[MAX_N], cis[MAX_N], ss[MAX_N];
int x0[MAX_N], x1[MAX_N], dp[MAX_N];

/* subroutines */

/* main */

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

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

  ps[0] = -1;
  for (int u = 0; u >= 0;) {
    vi &nbru = nbrs[u];
    int up = ps[u];

    if (cis[u] < nbru.size()) {
      int v = nbru[cis[u]++];
      if (v != up) {
	ps[v] = u;
	u = v;
      }
    }
    else {
      ss[u]++;

      int ux = x0[u] + 1;
      if (x1[u] > 0) ux += x1[u];
      else if (ss[u] - x0[u] >= 2) ux++;
      dp[u] = ux;

      if (up >= 0) {
	ss[up] += ss[u];
	if (x0[up] < ux) x1[up] = x0[up], x0[up] = ux;
	else if (x1[up] < ux) x1[up] = ux;
      }

      u = up;
    }
  }

  printf("%d\n", dp[0]);
  //for (int u = 0; u < n; u++) printf("%d ", dp[u]); putchar('\n');
  return 0;
}