/* TLE解 O(QNlogN) */ /* 次数2の頂点を縮約 */ /* priority_queueで値を管理 */ #include using namespace std; /** * @brief Scanner(高速入力) */ struct Scanner { public: explicit Scanner(FILE *fp) : fp(fp) {} template< typename T, typename... E > void read(T &t, E &... e) { read_single(t); read(e...); } private: static constexpr size_t line_size = 1 << 16; static constexpr size_t int_digits = 20; char line[line_size + 1] = {}; FILE *fp = nullptr; char *st = line; char *ed = line; void read() {} static inline bool is_space(char c) { return c <= ' '; } void reread() { ptrdiff_t len = ed - st; memmove(line, st, len); char *tmp = line + len; ed = tmp + fread(tmp, 1, line_size - len, fp); *ed = 0; st = line; } void skip_space() { while(true) { if(st == ed) reread(); while(*st && is_space(*st)) ++st; if(st != ed) return; } } template< typename T, enable_if_t< is_integral< T >::value, int > = 0 > void read_single(T &s) { skip_space(); if(st + int_digits >= ed) reread(); bool neg = false; if(is_signed< T >::value && *st == '-') { neg = true; ++st; } typename make_unsigned< T >::type y = *st++ - '0'; while(*st >= '0') { y = 10 * y + *st++ - '0'; } s = (neg ? -y : y); } template< typename T, enable_if_t< is_same< T, string >::value, int > = 0 > void read_single(T &s) { s = ""; skip_space(); while(true) { char *base = st; while(*st && !is_space(*st)) ++st; s += string(base, st); if(st != ed) return; reread(); } } template< typename T > void read_single(vector< T > &s) { for(auto &d: s) read(d); } }; /** * @brief Printer(高速出力) */ struct Printer { public: explicit Printer(FILE *fp) : fp(fp) {} ~Printer() { flush(); } template< bool f = false, typename T, typename... E > void write(const T &t, const E &... e) { if(f) write_single(' '); write_single(t); write< true >(e...); } template< typename... T > void writeln(const T &...t) { write(t...); write_single('\n'); } void flush() { fwrite(line, 1, st - line, fp); st = line; } private: FILE *fp = nullptr; static constexpr size_t line_size = 1 << 16; static constexpr size_t int_digits = 20; char line[line_size + 1] = {}; char small[32] = {}; char *st = line; template< bool f = false > void write() {} void write_single(const char &t) { if(st + 1 >= line + line_size) flush(); *st++ = t; } template< typename T, enable_if_t< is_integral< T >::value, int > = 0 > void write_single(T s) { if(st + int_digits >= line + line_size) flush(); if(s == 0) { write_single('0'); return; } if(s < 0) { write_single('-'); s = -s; } char *mp = small + sizeof(small); typename make_unsigned< T >::type y = s; size_t len = 0; while(y > 0) { *--mp = y % 10 + '0'; y /= 10; ++len; } memmove(st, mp, len); st += len; } void write_single(const string &s) { for(auto &c: s) write_single(c); } void write_single(const char *s) { while(*s != 0) write_single(*s++); } template< typename T > void write_single(const vector< T > &s) { for(size_t i = 0; i < s.size(); i++) { if(i) write_single(' '); write_single(s[i]); } } }; /** * @brief Union-Find * @docs docs/union-find.md */ struct UnionFind { vector< int > data; UnionFind() = default; explicit UnionFind(size_t sz) : data(sz, -1) {} bool unite(int x, int y) { x = find(x), y = find(y); if(x == y) return false; if(data[x] > data[y]) swap(x, y); data[x] += data[y]; data[y] = x; return true; } int find(int k) { if(data[k] < 0) return (k); return data[k] = find(data[k]); } int size(int k) { return -data[find(k)]; } bool same(int x, int y) { return find(x) == find(y); } vector< vector< int > > groups() { int n = (int) data.size(); vector< vector< int > > ret(n); for(int i = 0; i < n; i++) { ret[find(i)].emplace_back(i); } ret.erase(remove_if(begin(ret), end(ret), [&](const vector< int > &v) { return v.empty(); })); return ret; } }; int main() { Scanner in(stdin); Printer out(stdout); int N; in.read(N); vector< vector< int > > pre_g(N); vector< int > V(N); iota(begin(V), end(V), 0); using pi = pair< int, int >; vector< priority_queue< pi > > gg(N); vector< int > deg(N); for(int i = 1; i < N; i++) { int x, y; in.read(x, y); --x, --y; pre_g[x].emplace_back(y); pre_g[y].emplace_back(x); deg[x]++; deg[y]++; } // 次数2を縮約 UnionFind uf(N); vector< vector< int > > g(N); vector< vector< int > > h(N); vector< int > L(N, -1), R(N, -1), F(N, -1), T(N, -1); for(int i = 0; i < N; i++) { for(auto j: pre_g[i]) { if(pre_g[i].size() <= 2 and pre_g[j].size() <= 2) { uf.unite(i, j); h[i].emplace_back(j); } else { g[i].emplace_back(j); gg[i].emplace(V[j], j); } } } auto groups = uf.groups(); for(auto &group: groups) { if(group.size() <= 1) { continue; } vector< int > path; for(auto &p: group) { if(h[p].size() == 1) { auto dfs = [&](auto dfs, int idx, int par) -> void { path.emplace_back(idx); for(auto to: h[idx]) { if(to != par) dfs(dfs, to, idx); } }; dfs(dfs, p, -1); break; } } for(int i = 0; i < (int) path.size(); i++) { if(i > 0) L[path[i]] = path[i - 1]; if(i + 1 < (int) path.size()) R[path[i]] = path[i + 1]; F[path[i]] = path.front(); T[path[i]] = path.back(); } L[path.front()] = g[path.front()].empty() ? -1 : g[path.front()][0]; R[path.back()] = g[path.back()].empty() ? -1 : g[path.back()][0]; g[path.front()].emplace_back(path.back()); g[path.back()].emplace_back(path.front()); gg[path.front()].emplace(V[path.back()], path.back()); gg[path.back()].emplace(V[path.front()], path.front()); } auto modify = [&](int idx) { while(V[gg[idx].top().second] != gg[idx].top().first) { gg[idx].pop(); } }; int x = 0; int Q; in.read(Q); while(Q--) { int u, v; in.read(u, v); --u, --v; (u += x) %= N; (v += x) %= N; swap(V[u], V[v]); for(auto &to: g[u]) { gg[to].emplace(V[u], u); modify(to); } for(auto &to: g[v]) { gg[to].emplace(V[v], v); modify(to); } int p = -1; if(uf.size(u) >= 2) { if(F[u] == u) { if(L[u] == -1 or V[L[u]] < V[R[u]]) { p = u; u = T[u]; } else { p = u; u = L[u]; } } else if(T[u] == u) { if(R[u] == -1 or V[R[u]] < V[L[u]]) { p = u; u = F[u]; } else { p = u; u = R[u]; } } else if(V[L[u]] < V[R[u]]) { p = F[u]; u = T[u]; } else { p = T[u]; u = F[u]; } } for(;;) { modify(u); int to = gg[u].top().second; if(p != to) { p = u; u = to; } else if(deg[u] >= 2) { while(to == gg[u].top().second) { gg[u].pop(); modify(u); } int to2 = gg[u].top().second; gg[u].emplace(V[to], to); p = u; u = to2; } else { out.writeln(x = (u + 1)); break; } } } }