#include <bits/stdc++.h>
#define int long long
using namespace std;
const int mod=1e9+7;
const int N=1e5+5;
int n, q, deg[N];
vector<int> adj[N];
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> q;
for(int i=1; i<n; i++){
int u, v;
cin >> u >> v;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
deg[u]++;
deg[v]++;
}
int __=1;
while(__++<=q){
multiset<int> ms;
ms.emplace(1);
ms.emplace(n);
int d;
cin >> d;
for(int i=1; i<=d; i++){
int x;
cin >> x;
ms.emplace(x);
}
vector<int> num(ms.begin(),ms.end());
int sz=num.size();
vector<int> real;
int ans=0;
for(int i=0; i<sz; i++){
int cnt=0;
int j=i;
while(num[j]==num[i]) cnt++,j++;
real.emplace_back(num[i]);
if(cnt%2==0) real.emplace_back(num[i]);
ans+=(cnt-1)/2;
i=j-1;
}
int szz=real.size();
if(szz%2){
cout << -1 << "\n";
continue;
}
for(int i=0; i<szz/2; i++){
ans+=real[szz/2+i]+(real[szz/2+i]!=n)-real[i]+(real[i]!=1);
}
cout << ans << "\n";
}
}
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