#include <iostream> #include <vector> using std::cin; using std::cout; using std::endl; const int N = 100005; int n, q, u, v; char op; std::vector<int> g[N]; // Heavy Path Decomposition int cnt, id[N], rid[N], fa[N], dep[N], son[N], siz[N], top[N]; void dfs1(int, int); void dfs2(int, int); void modify_path(int); int query_path(int); // Segment Tree void pushup(int); void build(int, int, int); void modify(int, int, int); int query(int, int, int); int main() { cin >> n >> q; for (int i = 1; i < n; i++) { cin >> u >> v; g[u].push_back(v); g[v].push_back(u); } dfs1(1, 1); dfs2(1, 1); build(1, 1, n); modify_path(1); while (q--) { cin >> op >> u; if (op == 'C') { modify_path(u); } else { cout << query_path(u) << endl; } } return 0; } // === Heavy Path Decomposition === void dfs1(int u, int f) { fa[u] = f; siz[u] = 1; dep[u] = dep[f] + 1; for (int v : g[u]) { if (v == f) continue; dfs1(v, u); siz[u] += siz[v]; if (siz[son[u]] < siz[v]) son[u] = v; } } void dfs2(int u, int t) { id[u] = ++cnt; top[u] = t; if (!son[u]) return; dfs2(son[u], t); for (int v : g[u]) { if (v == fa[u]) continue; if (v == son[u]) continue; dfs2(v, v); } } inline void modify_path(int u) { modify(1, id[u], u); } int query_path(int u) { while (top[u] != 1) { int t = query(1, id[top[u]], id[u]); if (t != -1) return t; u = fa[top[u]]; } int t = query(1, 1, id[u]); if (t == -1) return 1; return t; } // === Segment Tree === struct node { int l, r, d; node() : l(0), r(0), d(-1) {} node(int _l, int _r) : l(_l), r(_r), d(-1) {} } tr[N << 2]; inline void pushup(int u) { node &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1]; if (left.d != -1 && right.d != -1) { if (dep[left.d] > dep[right.d]) { root.d = left.d; } else { root.d = right.d; } } else if (left.d != -1) { root.d = left.d; } else if (right.d != -1) { root.d = right.d; } else { root.d = -1; } } void build(int u, int l, int r) { tr[u] = node(l, r); if (l == r) return; int mid = l + r >> 1; build(u << 1, l, mid); build(u << 1 | 1, mid + 1, r); } void modify(int u, int x, int k) { if (tr[u].l == tr[u].r) { tr[u].d = k; return; } int mid = tr[u].l + tr[u].r >> 1; if (x <= mid) { modify(u << 1, x, k); } else { modify(u << 1 | 1, x, k); } pushup(u); } int query(int u, int l, int r) { if (l <= tr[u].l && tr[u].r <= r) return tr[u].d; int mid = tr[u].l + tr[u].r >> 1; int left = -1, right = -1; if (l <= mid) left = query(u << 1, l, r); if (r > mid) right = query(u << 1 | 1, l, r); if (left != -1 && right != -1) { if (dep[left] > dep[right]) return left; return right; } if (left != -1) return left; if (right != -1) return right; return -1; }