#pragma comment(linker, "/STACK:657772166")
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <queue>
#include <string>
#include <memory.h>
#include <iterator>
#define mem(A,X) memset(A,X,sizeof(A))
#define memo(A) memset(A,0,sizeof(A))
#define forn(I,B) for (int I=1;I<=(B);I++)
#define forg(H,V) for (int H=first[V];h;h=next[H])
#define rep(I,B) for (int I=0;I<(B);I++)
#define labs(X) (((X)>0)?(X):(-(X)))
#define ropen(X) freopen(X,"r",stdin)
#define wopen(X) freopen(X,"w",stdout)
#define pb push_back
#define mp make_pair
#define all(X) (X).begin(),(X).end()
#define sqr(X) ((X)*(X))

using namespace std;

typedef pair <int,int> pii;
typedef pair <long long,long long> pll;
typedef double ld;
typedef long long ll;
typedef vector<int> vi;
const int N=111111;
const int INF=111111111;
const double eps=1e-9;
const double pi=3.14159265358979;

int es[N+N],first[N],next[N+N],c,n,m,ans=INF,st[N],f[N+N],mx1[N+N],mx2[N+N],h[N];

inline void add(int x,int y){
    ++st[x];++st[y];
    next[++c]=first[x];first[x]=c;es[c]=y;
    swap(x,y);
    next[++c]=first[x];first[x]=c;es[c]=y;
}

int be(int x){
    return (x&1)?x+1:x-1;
}

void input(){
    ropen("pinetree.in");
    wopen("pinetree.out");
    scanf("%d",&n);
    forn(i,n-1){
        int x,y;
        scanf("%d%d",&x,&y);
        add(x,y);
    }
}

int calc(int x){
    if (f[x]!=-1) return f[x];
    if (st[es[x]]==1) return f[x]=0;
    mx1[x]=-1,mx2[x]=-1;
    for(h[es[x]]=first[es[x]];h[es[x]];h[es[x]]=next[h[es[x]]]){
        if (h[es[x]]==be(x)) continue;
        if (calc(h[es[x]])>mx2[x]) mx2[x]=calc(h[es[x]]);
        if (mx2[x]>mx1[x]) swap(mx2[x],mx1[x]);
    }
    f[x]=max(mx1[x],mx2[x]+1);
    if ((mx1[x]==0 || mx2[x]==0) && f[x]==0) ++f[x];
    return f[x];
}

int main(){
    input();
    mem(f,255);
    forn(i,c) if (f[i]==-1) calc(i);
    forn(i,n) if (st[i]==1) ans=min(ans,f[first[i]]);
    printf("%d\n",ans);
    return 0;
}