#include <cstdio>
#include <vector>
#include <queue>

using namespace std;

int N;
vector<int> g[100000];
int d[100000];

void init_bfs() {
  for(int i = 0; i < N; ++i) {
    d[i] = -1;
  }
}

void bfs(int source) {
  init_bfs();
  d[source] = 1;
  queue<int> q;
  q.push(source);
  while(!q.empty()) {
    int u = q.front();
    q.pop();
    for(int v : g[u]) {
      if(d[v] == -1) {
        d[v] = d[u] + 1;
        q.push(v);
      }
    }
  }
}

pair<int, int> max_idx() {
  int best_idx = 0;
  for(int i = 1; i < N; ++i) {
    if(d[best_idx] < d[i]) {
      best_idx = i;
    }
  }
  return make_pair(best_idx, d[best_idx]);
}

void add_edge(int x, int y) {
  g[x - 1].push_back(y - 1);
  g[y - 1].push_back(x - 1);
}

int main(int argc, char *argv[]) {
  freopen("darb.in", "r", stdin);
  freopen("darb.out", "w", stdout);

  scanf("%d", &N);
  for(int i = 0; i < N - 1; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    add_edge(x, y);
  }

  bfs(0);
  int far = max_idx().first;
  bfs(far);

  printf("%d\n", max_idx().second);

  return 0;
}