#include <bits/stdc++.h>
using namespace std;
#define LL long long
struct edge{
	LL to,nt;
}a[200005];
LL tree[100005];
LL num[100005],nxt[100005];
LL sum[100005];
LL dfn[100005],low[100005];
LL tmp[100005];
LL val[100005][2];
bool flag[100005];
LL deg[100005];
LL n,i,j,k,m,dfs_clock=0,sum1=0,ans=0,x,y,cnt=0;
LL root=0;
void add(LL x,LL y){
	a[++cnt].to=y;a[cnt].nt=nxt[x];nxt[x]=cnt;
}
LL cmp(LL x,LL y){
	return dfn[x]>dfn[y];
}
LL lowbit(LL x){
	return x & -x;
}
void insert(LL x,LL val){
	while(x<=n){
		tree[x]+=val;
		x+=lowbit(x);
	}
}
LL query(LL x){
	LL sum=0;
	while(x){
		sum+=tree[x];
		x-=lowbit(x);
	}
	return sum;
}
void dfs(LL father,LL x){
	dfn[x]=++dfs_clock;
	if(deg[x]==1) sum[x]=1;
	for(LL i=nxt[x];i;i=a[i].nt)
	  if(a[i].to!=father){
	  	dfs(x,a[i].to);
	  	sum[x]+=sum[a[i].to];
	  }
	low[x]=dfs_clock;
	if(x!=root){
		if(sum[x]%2==0){
			ans+=2;
			val[x][0]++;
		}
		else{
			ans+=1;
			val[x][1]++;
		}
	}
}
void dfs_getnum(LL father,LL x){
	for(LL i=nxt[x];i;i=a[i].nt) 
	  if(a[i].to!=father){
	  	val[a[i].to][0]+=val[x][0];
	  	val[a[i].to][1]+=val[x][1];
	  	dfs_getnum(x,a[i].to);
	  }
}
int main() {
    scanf("%lld%lld",&n,&m);
    for(i=1;i<n;i++){
    	scanf("%lld%lld",&x,&y);
    	add(x,y);
    	add(y,x);
    	deg[x]++;deg[y]++;
	}
	for(i=1;i<=n;i++){
		if(root==0 && deg[i]>1){
			root=i;
		}
		else if(deg[i]==1) sum1++;
	}
	dfs(0,root);
	dfs_getnum(0,root);
	LL now=0;
	LL cnt1=0;
	for(i=1;i<=m;i++){
		now=0;cnt1=0;
		scanf("%lld",&tmp[0]);
		for(j=1;j<=tmp[0];j++)
		  scanf("%lld",&tmp[j]);
		sort(tmp+1,tmp+tmp[0]+1,cmp);
		for(j=1;j<=tmp[0];j++){
			if(deg[tmp[j]]==1){
				if(flag[tmp[j]]==false){
					now++;
					flag[tmp[j]]=true;
				}
				else{
					cnt1++;
					LL num1=query(low[tmp[j]])-query(dfn[tmp[j]]-1);
					if(num1%2==0){
						now-=val[tmp[j]][0];
						now+=val[tmp[j]][1];
					}
					else{
						now+=val[tmp[j]][0];
						now-=val[tmp[j]][1];
					}
					now++;
					insert(dfn[tmp[j]],1);
				}
			}
			else{
				cnt1++;
				LL num1=query(low[tmp[j]])-query(dfn[tmp[j]]-1);
				if(num1%2==0){
					now-=val[tmp[j]][0];
					now+=val[tmp[j]][1];
				}
				else{
					now+=val[tmp[j]][0];
					now-=val[tmp[j]][1];
				}
				now++;
				insert(dfn[tmp[j]],1);
			}
		}
		if((sum1+cnt1)%2==1) printf("-1\n");
		else printf("%lld\n",now+ans);
		for(j=1;j<=tmp[0];j++){
			if(deg[tmp[j]]==1){
				if(flag[tmp[j]]==true) flag[tmp[j]]=false;
				else insert(dfn[tmp[j]],-1);
			}
			else{
				insert(dfn[tmp[j]],-1);
			}
		}
	}

	return 0;
}