//Proud of You//
#include <bits/stdc++.h>
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
using namespace std;
const int N = 1e5 + 17;
int n, q, a[N], sz[N], p[N], d[N], b[N], cnt, ans;
bool lz[4 * N];
int zch, head[N], ch[N], zp, pos[N], ar[N];
vector <int> adj[N];
struct node
{
int c1, c2;
node operator + (const node &o) const
{
return {c1 + o.c1, c2 + o.c2};
}
} st[4 * N];
inline void dfs (int u, int pr)
{
sz[u] = 1, p[u] = pr;
a[u] = (d[u] == 1), cnt += (d[u] == 1);
for (int v: adj[u])
{
if (v == pr)
{
continue;
}
dfs (v, u);
sz[u] += sz[v], a[u] += a[v];
}
if (u > 1)
{
ans += (a[u] % 2 ? 1 : 2);
}
}
inline void hld (int u, int pr)
{
if (!head[zch])
{
head[zch] = u;
}
ch[u] = zch, pos[u] = ++zp, ar[zp] = u;
int bc = 0;
for (int v: adj[u])
{
if (v == pr)
{
continue;
}
if (sz[bc] < sz[v])
{
bc = v;
}
}
if (bc)
{
hld (bc, u);
}
for (int v: adj[u])
{
if (v == pr || v == bc)
{
continue;
}
++zch;
hld (v, u);
}
}
inline void build (int id, int l, int r)
{
if (l == r)
{
st[id] = {a[ar[l]] % 2 == 1, a[ar[l]] % 2 == 0};
return;
}
int mid = l + r >> 1;
build (id * 2, l, mid);
build (id * 2 + 1, mid + 1, r);
st[id] = st[id * 2] + st[id * 2 + 1];
}
inline void down (int id)
{
swap (st[id * 2].c1, st[id * 2].c2);
lz[id * 2] ^= lz[id];
swap (st[id * 2 + 1].c1, st[id * 2 + 1].c2);
lz[id * 2 + 1] ^= lz[id];
lz[id] = 0;
}
inline void update (int id, int l, int r, int u, int v)
{
if (v < l || r < u)
{
return;
}
if (u <= l && r <= v)
{
ans -= st[id].c1 + st[id].c2 * 2;
swap (st[id].c1, st[id].c2);
ans += st[id].c1 + st[id].c2 * 2;
lz[id] ^= 1;
return;
}
int mid = l + r >> 1;
if (lz[id])
{
down(id);
}
update (id * 2, l, mid, u, v);
update (id * 2 + 1, mid + 1, r, u, v);
st[id] = st[id * 2] + st[id * 2 + 1];
}
inline void change (int u, int v)
{
while (ch[u] != ch[v])
{
update (1, 1, n, pos[head[ch[u]]], pos[u]);
u = p[head[ch[u]]];
}
update (1, 1, n, pos[v] + 1, pos[u]);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> q;
for (int i = 1, u, v; i < n; ++i)
{
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
++d[u], ++d[v];
}
dfs (1, 0);
hld (1, 0);
build (1, 1, n);
for (int i = 1, m; i <= q; ++i)
{
cin >> m;
for (int j = 1, u; j <= m; ++j)
{
cin >> u;
if (d[u] == 1)
{
--cnt;
}
else
{
change (u, 1);
}
++d[u], b[j] = u, ++ans, ++cnt;
}
if (cnt & 1)
{
cout << "-1\n";
}
else
{
cout << ans << "\n";
}
for (int j = 1, u; j <= m; ++j)
{
u = b[j], --d[u], --ans, --cnt;
if (d[u] == 1)
{
++cnt;
}
else
{
change (u, 1);
}
}
}
}
