// If I remember correctly, this is an CEOI problem that I had done. Still I barely remember anything :)
// It's true, vjudge spoiled it : )
#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "C:\debug.h"
#else
#define debug(...) 42
#endif
void test();
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
// int tests; cin >> tests; for (int t = 0; t < tests; ++t)
test();
}
struct st {
int n;
vector<int> s, lz, size;
st(int n = 0): n(n), s(4 * n), lz(4 * n), size(4 * n) {};
void bld(int id, int l, int r) {
size[id] = r - l + 1;
if (l == r) {
return;
}
int m = (l + r) / 2;
bld(id * 2, l, m);
bld(id * 2 + 1, m + 1, r);
s[id] = s[id * 2] + s[id * 2 + 1];
}
void flip(int u, int v, int id, int l, int r) {
if (u <= l && r <= v) {
app(id);
return;
}
psh(id);
int m = (l + r) / 2;
if (u <= m) {
flip(u, v, id * 2, l, m);
}
if (m < v) {
flip(u, v, id * 2 + 1, m + 1, r);
}
s[id] = s[id * 2] + s[id * 2 + 1];
}
void app(int id) {
lz[id] ^= 1;
s[id] = size[id] - s[id];
}
void psh(int id) {
if (lz[id]) {
app(id * 2);
app(id * 2 + 1);
lz[id] ^= 1;
}
}
int count() {
return s[1];
}
};
void test() {
int n, q; cin >> n >> q;
vector<vector<int>> g(n);
for (int i = 0; i < n - 1; ++i) {
int u, v; cin >> u >> v; --u, --v;
g[u].push_back(v);
g[v].push_back(u);
}
vector<int> head(n), pr(n), sz(n), tin(n);
auto dfs = [&](auto self, int u) -> void {
sz[u] = 1;
for (int v : g[u]) {
g[v].erase(find(g[v].begin(), g[v].end(), u));
pr[v] = u;
self(self, v);
sz[u] += sz[v];
}
};
auto hld = [&](auto self, int u, int h) -> void {
static int order = 0;
head[u] = h;
tin[u] = order++;
if (g[u].empty()) {
return;
}
int x = *max_element(g[u].begin(), g[u].end(), [&](int a, int b) {
return sz[a] < sz[b];
});
self(self, x, h);
for (int v : g[u]) {
if (v ^ x) {
self(self, v, v);
}
}
};
int root = 0;
for (int i = 0; i < n; ++i) {
if (g[i].size() > 1) {
root = i;
break;
}
}
dfs(dfs, root);
hld(hld, root, root);
st tree(n);
tree.bld(1, 0, n - 1);
auto flip = [&](int u) {
for (; head[u] ^ root; u = pr[head[u]]) {
tree.flip(tin[head[u]], tin[u], 1, 0, n - 1);
}
tree.flip(0, tin[u], 1, 0, n - 1);
};
int leafs = 0;
auto DFS = [&](auto self, int u) -> bool {
bool c = 0;
if (sz[u] == 1) {
++leafs;
c = 1;
} else for (int v : g[u]) {
c ^= self(self, v);
}
if (c) {
tree.flip(tin[u], tin[u], 1, 0, n - 1);
}
return c;
};
DFS(DFS, root);
while (q--) {
int D; cin >> D;
vector<int> add(D);
map<int, int> cnt;
int cur_leafs = leafs;
for (int i = 0; i < D; ++i) {
int a; cin >> a; --a;
++cnt[a];
++cur_leafs;
}
for (const auto &[x, y] : cnt) {
cur_leafs -= sz[x] == 1;
if (y % 2 != (sz[x] == 1)) {
flip(x);
}
}
if (cur_leafs & 1) {
cout << -1 << "\n";
} else {
int cnt_odd = tree.count();
cout << D + cnt_odd + (n - 1 - cnt_odd) * 2 << "\n";
}
for (const auto &[x, y] : cnt) if (y % 2 != (sz[x] == 1)) {
flip(x);
}
}
}
