#include <bits/stdc++.h>
using i64 = long long;
int main() {
int N, Q;
std::cin >> N >> Q;
std::vector<int> A(N - 1), B(N - 1);
std::vector<std::vector<int>> baseTree(N);
for (int i = 0; i < N - 1; ++i) {
std::cin >> A[i] >> B[i];
--A[i], --B[i];
baseTree[A[i]].push_back(B[i]);
baseTree[B[i]].push_back(A[i]);
}
std::vector<int> D(Q);
std::vector<std::vector<int>> L(Q);
for (int i = 0; i < Q; ++i) {
std::cin >> D[i];
L[i].resize(D[i]);
for (int &e : L[i]) {
std::cin >> e;
--e;
}
}
std::vector<int> degree(N);
for (int i = 0; i < N; ++i) {
degree[i] = (int)baseTree[i].size();
}
const int nonLeafV = (std::max_element(degree.begin(), degree.end()) - degree.begin());
const int countBaseLeaf = std::count(degree.begin(), degree.end(), 1);
std::vector<bool> isEven(N);
std::vector<int> parent(N);
auto dfs = [&](auto &&self, const int v, const int p) -> bool {
parent[v] = p;
bool res = false;
if (baseTree[v].size() == 1) {
res = true;
}
for (const int t : baseTree[v]) {
if (t == p) {
continue;
}
res ^= self(self, t, v);
}
isEven[v] = not res;
return res;
};
dfs(dfs, nonLeafV, -1);
int baseAnswer = N - 1 + std::count(isEven.begin(), isEven.end(), true);
for (int q = 0; q < Q; ++q) {
int countLeaf = countBaseLeaf;
int answer = baseAnswer;
auto toup = [&](auto &&self, const int v) -> void {
answer -= isEven[v];
isEven[v] = not isEven[v];
answer += isEven[v];
if (parent[v] != -1) self(self, parent[v]);
};
for (int i = 0; i < D[q]; ++i) {
const int v = L[q][i];
if (degree[v] != 1) {
++countLeaf;
++answer;
toup(toup, v);
} else {
++answer;
}
++degree[v];
}
if (countLeaf % 2 == 1) {
answer = -1;
}
std::cout << answer - isEven[nonLeafV] << std::endl;
for (int i = 0; i < D[q]; ++i) {
const int v = L[q][i];
--degree[v];
if (degree[v] != 1) {
toup(toup, v);
}
}
}
}
