#include <bits/stdc++.h>

using namespace std;

#define forn(i, n) for (int i = 0; i < (int)(n); ++i)

struct Tree {
	Tree* l;
	Tree* r;
	Tree* p;
};

void dfs(Tree *v, vector<Tree*>& euler) {
	if (!v) {
		return;
	}
	euler.push_back(v);
	dfs(v->l);
	dfs(v->r);
}

Tree* findLca(Tree* t, vector<Tree*> lst) {
	unordered_set<Tree*> s;
	forn (i, lst.size()) {
		s.insert(lst[i]);
	}
	vector<Tree*> euler;
	dfs(t, euler);
	int n = euler.size();
	Tree* l = nullptr;
	Tree* r = nullptr;
	forn (i, n) {
		if (s.find(euler[i]) != s.end()) {
			if (!l) {
				l = euler[i];
			}
			r = euler[i];
		}
	}
	int lHeight = 0;
	Tree *v = l;
	while (v) {
		++lHeight;
		v = v->p;
	}
	int rHeight = 0;
	v = r;
	while (v) {
		++rHeight;
		v = v->p;
	}
	if (lHeight < rHeight) {
		swap(l, r);
		swap(lHeight, rHeight);
	}
	while (lHeight > rHeight) {
		l = l->p;
		--lHeight;
	}
	while (l != r) {
		l = l->p;
		r = r->p;
	}
	return r;
}

int main() {
}