#include using namespace std; // #include // using namespace atcoder; /* alias */ using ull = unsigned long long; using ll = long long; using pii = pair; using pll = pair; using vi = vector; using vll = vector; using vd = vector; using vs = vector; using vb = vector; using vpii = vector>; using vpll = vector>; using vvi = vector>; using vvll = vector>; using vvd = vector>; using vvs = vector>; using vvb = vector>; template using min_priority_queue = priority_queue, greater>; /* define */ #define MOD 998244353 // #define MOD 1000000007 #define INF (1LL << 60) #define elif else if #define pb push_back #define pf push_front #define fi first #define se second #define all(obj) (obj).begin(), (obj).end() #define YESNO(bool) cout << (bool ? "YES\n" : "NO\n") #define YesNo(bool) cout << (bool ? "Yes\n" : "No\n") #define yesno(bool) cout << (bool ? "yes\n" : "no\n") template bool chmax(T &a, const T &b) {if(a bool chmin(T &a, const T &b) {if(b= 0; i--) #define rrepd(i, n) for(ll i = (n); i >= 1; i--) #define fore(i, a) for(auto &i: a) /* vector */ template T vmax(vector &array){ T ret = array[0]; for(T a: array) chmax(ret, a); return ret; } template T vmin(vector &array){ T ret = array[0]; for(T a: array) chmin(ret, a); return ret; } template T sum(vector &array){ T ret = 0; for(T a:array) ret += a; return ret; } template void list_set(vector &array){ sort(all(array)); array.erase(unique(all(array)),array.end()); } template int bisect_left(vector &array, T key){ return lower_bound(all(array),key) - array.begin(); } template int bisect_right(vector &array, T key){ return upper_bound(all(array),key) - array.begin(); } /* string */ ll string_to_ll(string n){ ll ret = 0, k = 1; while(n.length() > 0){ ret += k * (n.back() - '0'); n.pop_back(); k *= 10; } return ret; } string ll_to_string(ll n){ string ret = ""; while(n > 0){ ret.pb((n % 10) + '0'); n /= 10; } reverse(all(ret)); return ret; } struct popopo{ popopo(){ cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(15); }; } popopoppo; // n = 1,...,N に対して、n % A < B を満たすものの数 ll Count_of_n_mod_A_less_than_B(ll N, ll A, ll B){ return N / A * min(A, B) + min(N % A, B - 1); } bool include(ll l, ll r, ll x) { return l <= x && x < r; } /* IN/OUT */ int scan() { return getchar(); } void scan(int &a) { cin >> a; } void scan(long long &a) { cin >> a; } void scan(char &a) { cin >> a; } void scan(double &a) { cin >> a; } void scan(string &a) { cin >> a; } template void scan(pair &p) { scan(p.first), scan(p.second); } template void scan(vector &); template void scan(vector &a) { for(auto &i : a) scan(i); } void IN(){} template void IN(Head& head, Tail &...tail){ scan(head); IN(tail...); } #define INT(...) int __VA_ARGS__; IN(__VA_ARGS__) #define LL(...) ll __VA_ARGS__; IN(__VA_ARGS__) #define STR(...) string __VA_ARGS__; IN(__VA_ARGS__) #define VEC(type, name, size) vector name(size); IN(name) #define VECS(type, name, size) vector name(size + 1); for(int i = 1; i <= size; i++) scan(name[i]) void OUT(){ cout << "\n"; } template void output(T a){ cout << a; } template void output(vector v){ for(int i = 0; i < v.size(); i++) cout << v[i] << (i == v.size() - 1 ? "" : " "); } template void OUT(const Head &head, const Tail &...tail) { output(head); if(sizeof...(tail)) cout << " "; OUT(tail...); } void FLASH(){ cout << endl; } template void FLASH(const Head &head, const Tail &...tail) { output(head); if(sizeof...(tail)) cout << " "; FLASH(tail...); } namespace kyo { long long bisect(long long ok, long long ng, function is_ok) { while (abs(ok - ng) > 1) { long long mid = ok + (ng - ok) / 2; (is_ok(mid) ? ok : ng) = mid; } return ok; } } template struct Tree { struct edge{ int to; T cost; }; vector> G; vector> parent; vector unweighted_dist; vector weighted_dist; Tree(int n) : G(n) {} void add_edge(int u, int v) { add_edge(u, v, T(1)); } void add_edge(int u, int v, T w) { G[u].push_back({v, w}); G[v].push_back({u, w}); } vector calc_dist(int root = 0) { vector dist(G.size(), -1); dist[root] = 0; queue que; que.push(root); while (!que.empty()) { int v = que.front(); que.pop(); for (auto e: G[v]) { if (dist[e.to] != -1) continue; dist[e.to] = dist[v] + e.cost; que.push(e.to); } } return dist; } tuple diameter() { vector dist = calc_dist(); int v = max_element(dist.begin(), dist.end()) - dist.begin(); dist = calc_dist(v); int u = max_element(dist.begin(), dist.end()) - dist.begin(); return { dist[u], u, v }; } vector path(int u, int v) { vector dist = calc_dist(u); vector path; while (v != u) { path.push_back(v); for (auto e: G[v]) { if (dist[e.to] == dist[v] - e.cost) { v = e.to; break; } } } path.push_back(u); reverse(path.begin(), path.end()); return path; } void lca_build(int root = 0) { int V = G.size(); int K = 1; while ((1 << K) < V) K++; parent.assign(K, vector(V, -1)); unweighted_dist.assign(V, -1); auto unweighted_dfs = [this](auto&& self, int v, int p, int d) -> void { parent[0][v] = p; unweighted_dist[v] = d; for (auto e: G[v]) { if (e.to == p) continue; self(self, e.to, v, d + 1); } }; unweighted_dfs(unweighted_dfs, root, -1, 0); for (int k = 0; k + 1 < K; k++) { for (int v = 0; v < V; v++) { if (parent[k][v] < 0) parent[k + 1][v] = -1; else parent[k + 1][v] = parent[k][parent[k][v]]; } } weighted_dist.assign(V, -1); weighted_dist[root] = 0; queue que; que.push(root); while (!que.empty()) { int v = que.front(); que.pop(); for (auto e: G[v]) { if (weighted_dist[e.to] == -1 || weighted_dist[e.to] > weighted_dist[v] + e.cost) { weighted_dist[e.to] = weighted_dist[v] + e.cost; que.push(e.to); } } } } int lca(int u, int v) { if (parent.size() == 0) lca_build(); if (unweighted_dist[u] < unweighted_dist[v]) swap(u, v); int K = parent.size(); for (int k = 0; k < K; k++) { if ((unweighted_dist[u] - unweighted_dist[v]) >> k & 1) { u = parent[k][u]; } } if (u == v) return u; for (int k = K - 1; k >= 0; k--) { if (parent[k][u] != parent[k][v]) { u = parent[k][u]; v = parent[k][v]; } } return parent[0][u]; } T dist(int u, int v) { if (weighted_dist.size() == 0) lca_build(); return weighted_dist[u] + weighted_dist[v] - 2 * weighted_dist[lca(u, v)]; } }; int main() { LL(N, Q); Tree tree(N); vll out(N, 0); rep(i, N - 1) { LL(A, B); tree.add_edge(A - 1, B - 1); out[A - 1]++; out[B - 1]++; } while (Q--) { LL(s, t); s--; t--; ll dist = tree.dist(s, t); if (dist % 2 != 0) { OUT(0); continue; } ll lca = tree.lca(s, t); if (tree.dist(lca, s) < tree.dist(lca, t)) swap(s, t); // s から dist / 2 個前の親 ll d = dist / 2; rep(i, tree.parent.size()) { if ((d >> i) & 1) { s = tree.parent[i][s]; } } OUT(out[s] - 1); } }