#include <vector>
#include <bit>
#include <bitset>
#include <cstdint>

class TreeAncestor {
private:
    std::vector<std::vector<int>> predecessor;
    std::vector<int> depth;
public:
    TreeAncestor(std::vector<std::pair<int, int>>& edges) {
        int n = edges.size() + 1;
        int m = bit_width((unsigned)n);
        predecessor.resize(n, std::vector<int>(m, -1));
        depth.resize(n, 0);

        std::vector<std::vector<int>> graph(n);
        for (const auto& [u, v] : edges) {
            graph[u].emplace_back(v);
            graph[v].emplace_back(u);
        }

        auto dfs = [&](auto&& dfs, int x, int fa) -> void {
            predecessor[x][0] = fa;
            for (auto y : graph[x]) {
                if (y != fa) {
                    depth[y] = depth[x] + 1;
                    dfs(dfs, y, x);
                }
            }
        };
        dfs(dfs, 0, -1);

        for (int i = 1; i < m; i++) {
            for (int x = 0; x < n; x++) {
                if (int p = predecessor[x][i - 1]; p != -1) {
                    predecessor[x][i] = predecessor[p][i - 1];
                }
            }
        }
    }

    int getKthAncestor(int node, int k) {
        //for (int i = 0; i < bit_width((unsigned)k) && node != -1; i++) {
        //    if (k >> i & 1) {
        //        node = predecessor[node][i];
        //    }
        //}
        for (; k && node != -1; k &= k - 1) {
            node = predecessor[node][countr_zero(unsigned(k))];
        }
        return node;
    }
    int getLowestCommonAncestor(int u, int v) {
        if (depth[u] > depth[v]) {
            std::swap(u, v);
        }

        for (int k = depth[v] - depth[u]; k; k &= k - 1) {
            v = predecessor[v][countr_zero(unsigned(k))];
        }

        if (u != v) {
            for (int i = predecessor[u].size() -1; i >= 0; i--) {
                int pu = predecessor[u][i], pv = predecessor[v][i];
                if (pu != pv) {
                    u = pu, v = pv;
                }
            }
        }
        return predecessor[u][0];
    }
};