#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=14449999999999994;
ll mod=1000000007;
int main(){
    ll n;
    cin >> n;
    vector<vector<ll>>g(n);
    for (ll i = 0; i < n-1; i++)
    {
        ll a,b;
        cin >> a >> b;a--,b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    vector<ll>memo(n,inf);
    memo[0]=0;
    queue<ll>que;
    que.push(0);
    while (!que.empty())
    {
        ll v=que.front();
        que.pop();
        for (ll i = 0; i < g[v].size(); i++)
        {
            if (memo[g[v][i]]>memo[v]+1)
            {
                memo[g[v][i]]=memo[v]+1;
                que.push(g[v][i]);
            }
        }
    }
    ll id=0,x=0;
    for (ll i = 0; i < n; i++)
    {
        if (memo[i]>x)
        {
            id=i;
            x=memo[i];
        }
    }
    que.push(id);
    for (ll i = 0; i < n; i++)
    {
        memo[i]=inf;
    }
    memo[id]=0;
    while (!que.empty())
    {
        ll v=que.front();
        que.pop();
        for (ll i = 0; i < g[v].size(); i++)
        {
            if (memo[g[v][i]]>memo[v]+1)
            {
                memo[g[v][i]]=memo[v]+1;
                que.push(g[v][i]);
            }
        }
    }
    x=0;
    for (ll i = 0; i < n ; i++)
    {
        x=max(x,memo[i]);
    }
    cout << 2*(n-1)-x << endl;
}