#include "bits/stdc++.h"
using namespace std;
#define ar array
typedef int64_t ll;
const int N = 1e5 + 5;
vector<int> edges[N];
int sub[N], nw[N], res;
int is[N];
void dfs(int u, int p = -1){
sub[u] = nw[u] + is[u];
for(auto x : edges[u]){
if(x == p) continue;
dfs(x, u);
sub[u] += sub[x];
}
//~ cout<<u<<" "<<sub[u]<<"\n";
if(!(sub[u] & 1)){
//~ cout<<u<<"\n";
res++;
}
}
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
int n, q; cin>>n>>q;
for(int i=1;i<n;i++){
int a, b; cin>>a>>b;
edges[a].push_back(b);
edges[b].push_back(a);
}
int cnt = 0;
for(int i=1;i<=n;i++){
is[i] = ((int)edges[i].size() == 1);
cnt += is[i];
}
for(int i=0;i<q;i++){
int d; cin>>d;
vector<int> t, tmp;
for(int x=0;x<d;x++){
int p; cin>>p;
nw[p]++;
t.push_back(p);
if(is[p]){
is[p]--;
cnt--;
}
}
res = 0, dfs(1);
if((cnt + d) & 1){
cout<<-1<<"\n";
} else {
cout<<n - 1 + d + res - 1<<"\n";
}
for(auto p : t){
nw[p]--;
if((int)edges[p].size() == 1 && !is[p]){
is[p] = 1;
cnt++;
}
}
}
}
