#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MAXN = 2e5 + 5;
ll n, q, d, initAns, ans = 0, root, parr[MAXN], query[MAXN], plusarr[MAXN];
bool parity[MAXN], isLeaf[MAXN], processed[MAXN];
vector<ll> adjl[MAXN];
void dfs(ll now, ll par) {
parity[now] = 0;
parr[now] = par;
isLeaf[now] = (adjl[now].size() == 1);
if(isLeaf[now]) {parity[now] = 1;}
else {
for(ll nxt : adjl[now]) {
if(nxt == par) {continue ;}
dfs(nxt, now);
parity[now] ^= parity[nxt];
}
}
if(parity[now] == 0) {ans++;}
}
void hld() {}
void build() {
dfs(root, root);
}
bool getRoot() {
return parity[root];
}
void addLeaf(ll node) {
ll now = node;
while(true) {
parity[now] ^= 1;
if(parr[now] == now) {break ;}
now = parr[now];
}
}
ll ask(ll node) {
ll out = 0, now = node;
while(true) {
out += (parity[now] == 0);
if(parr[now] == now) {break ;}
now = parr[now];
}
return out;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n >> q;
ans = n-1;
for (int i = 0; i < n-1; ++i) {
ll a, b;
cin >> a >> b;
adjl[a].push_back(b);
adjl[b].push_back(a);
if(adjl[a].size() > 1) {root = a;}
else if(adjl[b].size() > 1) {root = b;}
}
build();
initAns = ans;
while(q--) {
// Input
ans = initAns;
cin >> d;
ans += d;
for (int i = 0; i < d; ++i) {
cin >> query[i];
plusarr[query[i]]++;
}
for (int i = 0; i < d; ++i) {
ll now = query[i];
if(processed[now]) {continue ;}
processed[now] = true;
if((plusarr[now]-isLeaf[now]) % 2) {
ans -= ask(now);
addLeaf(now);
ans += ask(now);
}
}
if(getRoot() == 1) {
cout << "-1\n";
} else {
cout << (ans-1) << "\n";
}
// Reset
for (int i = 0; i < d; ++i) {processed[query[i]] = false;}
for (int i = 0; i < d; ++i) {
ll now = query[i];
if(processed[now]) {continue ;}
processed[now] = true;
if((plusarr[now]-isLeaf[now]) % 2) {
addLeaf(now);
}
}
for (int i = 0; i < d; ++i) {processed[query[i]] = false; plusarr[query[i]] = 0;}
}
return 0;
}
