#include "bits/stdc++.h"
using namespace std;
const int MAXN = 100'000;
const int K = 350;
int n, m, q;
vector<int> adj[MAXN];
vector<int> revAdj[MAXN];
vector<pair<int, int>> kvals[MAXN];
bool done[MAXN];
int dp[MAXN];
bool busy[MAXN];
void dfs(int v) {
if (!size(kvals[v]))
kvals[v].push_back({0, v});
for (auto u : revAdj[v]) {
if (!size(kvals[u]))
dfs(u);
vector<pair<int, int>> nxt;
auto itv = begin(kvals[v]);
auto itu = begin(kvals[u]);
while (itv != end(kvals[v]) && itu != end(kvals[u]) && size(nxt) < K) {
if (done[itv->second]) {
itv++;
continue;
}
if (done[itu->second]) {
itu++;
continue;
}
if (itv->first > itu->first + 1) {
done[itv->second] = true;
nxt.push_back(*(itv++));
} else {
done[itu->second] = true;
nxt.push_back({itu->first + 1, itu->second});
itu++;
}
}
while (itv != end(kvals[v]) && size(nxt) < K) {
if (!done[itv->second]) {
done[itv->second] = true;
nxt.push_back(*itv);
}
itv++;
}
while (itu != end(kvals[u]) && size(nxt) < K) {
if (!done[itu->second]) {
done[itu->second] = true;
nxt.push_back({itu->first + 1, itu->second});
}
itu++;
}
for (auto i : nxt) done[i.second] = false;
swap(kvals[v], nxt);
}
}
void solve(int v) {
done[v] = true;
if (!busy[v])
dp[v] = 0;
for (auto u : revAdj[v]) {
if (!done[u])
solve(u);
if (dp[u] == -1) continue;
dp[v] = max(dp[v], dp[u] + 1);
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> q;
for (int i = 0; i < m; i++) {
int a, b;
cin >> a >> b;
a--, b--;
adj[a].push_back(b);
revAdj[b].push_back(a);
}
for (int i = 0; i < n; i++) {
if (size(adj[i])) continue;
dfs(i);
}
while (q--) {
int t, y;
cin >> t >> y;
t--;
vector<int> b(y);
for (int i = 0; i < y; i++) {
cin >> b[i];
b[i]--;
busy[b[i]] = true;
}
int ans = -1;
if (y < K) {
for (auto i : kvals[t])
if (!busy[i.second]) {
ans = i.first;
break;
}
} else {
for (int i = 0; i < n; i++) dp[i] = -1;
memset(done, false, sizeof done);
solve(t);
ans = dp[t];
}
cout << ans << '\n';
for (auto i : b) busy[i] = false;
}
}
