#include <string>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using ull = unsigned long long;
using ll = long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int N;
vector<vector<int>> E;
vector<int> D;
vector<int> P;
vector<int> ans2;
vector<int> ans;

void dfs(int p){
  for(int e:E[p]) if(D[e]==-1){
    P[e] = p;
    D[e] = D[p]+1;
    dfs(e);
  }
}

void dfs2(int p){
  if(D[P[p]]==-1){
    int e=P[p];
    D[e]=0;
    ans2[e] = ans2[p] + 1;
    dfs2(e);
    ans2[p] = ans[e] + 1;
  }
  for(int e:E[p]) if(D[e]==-1){
    D[e]=0;
    ans2[e] = ans2[p] + 1;
    dfs2(e);
    ans2[p] = ans[e] + 1;
  }
  ans[p] = ans2[p];
}

int main(){
  scanf("%d",&N);
  E.resize(N);
  rep(i,N-1){
    int u,v; scanf("%d%d",&u,&v); u--; v--;
    E[u].push_back(v);
    E[v].push_back(u);
  }

  D.assign(N,-1);
  P.assign(N,-1);
  D[0]=0; dfs(0);
  int s=0; rep(i,N) if(D[s]<D[i]) s=i;
  D.assign(N,-1);
  P.assign(N,-1);
  D[s]=0; dfs(s);
  int t=0; rep(i,N) if(D[t]<D[i]) t=i;
  printf("%d\n",(N-1)*2-D[t]);
  return 0;
}