#include<iostream>
#include<algorithm>
#include<vector>

using namespace std;

#define sz(x) (int)(x.size())
#define rep(i,a,b) for(int i=a;i<b;++i)
#define pb push_back
///////////////////////

int const N = 3e5 + 41;
int const M = 25;

int n;
int d[N];
vector<int> e[N];

int dfs(int u, int p){
	int atleastOne = 0;
	int atleastTwo = 0;
	rep(i, 0, sz(e[u])){
		int to = e[u][i];
		if(to == p) continue;
		int res = dfs(to, u);
		atleastTwo|= (atleastOne & res);
		atleastOne |= res;
	}
	int ret;
	rep(i, 0, M){
		if( ((1<<i) > atleastTwo) && !(atleastOne&(1<<i)) ){
			ret = i;
			break;
		}
	}
	
	int result = (1 << ret);
	rep(i, ret, M){
		result |= ((1 << i) & atleastOne);
	}

	return d[u] = result;
}

void solve(){
	cin >> n;
	rep(i, 0, n-1){
		int u, v;
		cin >> u >> v;
		--u;--v;
		e[u].pb(v);
		e[v].pb(u);
	}
	int ansMask = dfs(0, 0);
	int ans = -1;
	while(ansMask){
		++ans;
		ansMask /= 2;
	}
	cout << ans << endl;
}

int main(){
#ifdef _DEBUG
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
#endif

	solve();

	return 0;
}