#include <bits/stdc++.h>
using i64 = long long;
struct HLD {
int n;
std::vector<std::vector<int>> tree;
std::vector<int> st, in, out, head, parent;
HLD(std::vector<std::vector<int>> tree_, int root) {
tree = tree_;
n = tree.size();
st.resize(n);
in.resize(n);
out.resize(n);
head.resize(n);
parent.resize(n);
dfs1(root, -1);
int x = 0;
head[root] = root;
dfs2(root, -1, x);
}
void dfs1(int v, int p) {
parent[v] = p;
st[v] = 1;
for (int &t : tree[v]) {
if (t == p) {
continue;
}
dfs1(t, v);
st[v] += st[t];
if (st[tree[v][0]] < st[t]) {
std::swap(tree[v][0], t);
}
}
}
void dfs2(int v, int p, int &id) {
in[v] = id++;
for (const int t : tree[v]) {
if (t == p) {
continue;
}
head[t] = tree[v][0] == t ? head[v] : t;
dfs2(t, v, id);
}
out[v] = id;
}
template <class F>
void query(int v, const F &func) {
while (v != -1) {
func(in[head[v]], in[v] + 1);
v = parent[head[v]];
}
}
};
struct node {
int a, b;
};
node op(node a, node b) {
return {a.a + b.a, a.b + b.b};
}
node e() {
return {0, 0};
}
node map(bool x, node b) {
if (x) std::swap(b.a, b.b);
return b;
}
bool composite(bool x, bool y) {
return x xor y;
}
bool id() {
return false;
}
class lazySegtree {
int n, size, lg;
std::vector<node> data;
std::vector<bool> lazy;
void update(int i) {
data[i] = op(data[2 * i], data[2 * i + 1]);
}
void cv(int i, bool f) {
data[i] = map(f, data[i]);
if (i < size) {
lazy[i] = composite(f, lazy[i]);
}
}
void push(int i) {
cv(2 * i, lazy[i]);
cv(2 * i + 1, lazy[i]);
lazy[i] = id();
}
public:
lazySegtree(int n_) {
n = n_;
size = 1;
lg = 0;
while (size < n) {
++lg;
size *= 2;
}
data.assign(2 * size, e());
lazy.assign(size, id());
}
void set(int i, node v) {
i += size;
for (int d = lg; d >= 1; --d) {
push(i >> d);
}
data[i] = v;
for (int d = 1; d <= lg; ++d) {
update(i >> d);
}
}
node fold(int l, int r) {
l += size, r += size;
for (int d = lg; d >= 1; --d) {
if (((l >> d) << d) != l) push(l >> d);
if (((r >> d) << d) != r) push((r - 1) >> d);
}
node retL = e(), retR = e();
while (l < r) {
if (l & 1) retL = op(retL, data[l++]);
if (r & 1) retR = op(data[--r], retR);
l /= 2;
r /= 2;
}
return op(retL, retR);
}
void apply(int l, int r, bool f) {
l += size, r += size;
for (int d = lg; d >= 1; --d) {
if (((l >> d) << d) != l) push(l >> d);
if (((r >> d) << d) != r) push((r - 1) >> d);
}
int l2 = l, r2 = r;
while (l < r) {
if (l & 1) cv(l++, f);
if (r & 1) cv(--r, f);
l /= 2;
r /= 2;
}
l = l2, r = r2;
for (int d = 1; d <= lg; ++d) {
if (((l >> d) << d) != l) update(l >> d);
if (((r >> d) << d) != r) update((r - 1) >> d);
}
}
};
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;
HLD hld(baseTree, nonLeafV);
lazySegtree seg(N);
for (int i = 0; i < N; ++i) {
node v = {isEven[i] ? 1 : 0, isEven[i] ? 0 : 1};
seg.set(hld.in[i], v);
}
assert(seg.fold(1, N).a == std::count(isEven.begin(), isEven.end(), true) - isEven[nonLeafV]);
for (int q = 0; q < Q; ++q) {
int countLeaf = countBaseLeaf;
int answer = baseAnswer;
auto toup = [&](const int v) -> void {
hld.query(v, [&](int l, int r) {
seg.apply(l, r, true);
});
};
for (int i = 0; i < D[q]; ++i) {
const int v = L[q][i];
if (degree[v] != 1) {
++countLeaf;
++answer;
toup(v);
} else {
++answer;
}
++degree[v];
}
answer += seg.fold(1, N).a;
if (countLeaf % 2 == 1) {
answer = -1;
}
std::cout << answer << std::endl;
for (int i = 0; i < D[q]; ++i) {
const int v = L[q][i];
--degree[v];
if (degree[v] != 1) {
toup(v);
}
}
}
}
