#include <iostream>
#include <fstream>
#include <algorithm>
#include <cmath>
#include <limits.h>
#include <chrono>
#include <numeric>
#include <iomanip>

#include <vector>
#include <string>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <bitset>
#include <deque>  
#include <stack>
#include <queue>
#include <list>

using namespace std;

#include <ext/pb_ds/assoc_container.hpp>

using namespace __gnu_pbds;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<string, string> pss;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vii;
typedef vector<pll> vll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<bool> vb;
typedef vector<vb> vvb;

template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
 
double EPS = 1e-9;
int INF = 1000000005;
long long INFF = 1000000000000000005LL;
double PI = acos(-1);

#define M 1000000007

#define rall(x) (x).rbegin(), (x).rend()
#define all(x) (x).begin(), (x).end()

// auto lim=unique(all(v));
// v.resize(distance(v.begin(), lim));

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

struct pair_custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    template <class T1, class T2>
    size_t operator()(const pair<T1, T2>& p) const
    {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();

        auto hash1 = splitmix64(p.first+FIXED_RANDOM);
        auto hash2 = splitmix64(p.second+FIXED_RANDOM);
 
        return hash1^hash2;
    }
};

ll gcd(ll a,ll b){
    ll r;
    while(b){
        r=a%b;
        a=b;
        b=r;
    }
    return a;
}

ll lcm(ll a,ll b){
    return a*b/gcd(a,b);
}

template<class T> T nxt() {
    T x;
    cin >> x;
    return x;
}

void dfsDiameter(int x,vb& u,vvi& v,vi& d){
    u[x]=1;
    for(auto y:v[x]){
        if(!u[y]){
            d[y]=d[x]+1;
            dfsDiameter(y,u,v,d);
        }
    }
}

// get the diameter of a tree with nodes from 1 to n
// Diameter - the length of the longest path from 2 nodes/counting the edges
int getDiameter(vvi& v){
    int n=v.size()-1;

    if(n<=3){
        return n-1;
    }

    int a=1,b,lb=0;
    vb u1(n+1),u2(n+1);
    vi d1(n+1),d2(n+1);
    dfsDiameter(a,u1,v,d1);

    for(int i=1;i<=n;++i){
        if(lb<d1[i]){
            lb=d1[i];
            b=i;
        }
    }

    dfsDiameter(b,u2,v,d2);
    int ans=0;
    for(int i=1;i<=n;++i){
        ans=max(ans,d2[i]);
    }

    return ans;
}


void Solve(){
    int n;
    cin>>n;
    vvi v(n+1);
    for(int i=0;i<n-1;++i){
        int x,y;
        cin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }

    cout<<getDiameter(v)+1;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    freopen("darb.in", "r", stdin);
    freopen("darb.out", "w", stdout);

    // std::string file="";
    // std::ifstream in(file+".in");
    // std::streambuf *cinbuf = std::cin.rdbuf(); //save old buf
    // cin.rdbuf(in.rdbuf()); //redirect std::cin
    
    // std::ofstream out(file+".out");
    // std::streambuf *coutbuf = std::cout.rdbuf(); //save old buf
    // cout.rdbuf(out.rdbuf()); //redirect std::cout

    Solve();

    // std::cin.rdbuf(cinbuf);   //reset to standard input again
    // std::cout.rdbuf(coutbuf); //reset to standard output again

    return 0;
}