#include <bits/stdc++.h>
#define endl '\n'
#pragma GCC optimize("O3" , "Ofast" , "unroll-loops")
#pragma GCC target("avx2")
using namespace std;
const int MAXN = 1e5;
const int block = 130;
int n, m, q, x, y, dp[MAXN + 5], mx[MAXN + 5];
vector<pair<int,int>>vals[MAXN + 5];
vector<int>v[MAXN + 5], v1[MAXN + 5];
bool used[MAXN + 5], is[MAXN + 5], canR[MAXN + 5], vis[MAXN + 5];
inline void dfss(int node)
{
used[node] = true;
for(auto i: v[node])
{
if(!used[i])dfss(i);
if(canR[i])
{
canR[node] = true;
dp[node] = max(dp[node], dp[i] + 1);
}
}
}
inline void solve1()
{
for(int i = 1; i <= n; i++)
{
used[i] = false;
is[i] = false;
dp[i] = 0;
canR[i] = false;
}
for(int i = 1; i <= y; i++)
{
int a; cin >> a;
is[a] = true;
}
canR[x] = true;
for(int i = 1; i <= n; i++)
{
if(!used[i] && i != x)
{
dfss(i);
}
}
int ans = -1;
for(int i = 1; i <= n; i++)
{
if(canR[i] && !is[i])
{
ans = max(ans, dp[i]);
}
}
cout << ans << endl;
}
inline void dfs(int node)
{
vis[node] = true;
vector<int>ve;
ve.push_back(node);
mx[node] = 0;
for(auto i: v1[node])
{
if(!vis[i])
dfs(i);
for(auto j: vals[i])
{
ve.push_back(j.second);
mx[j.second] = max(mx[j.second], j.first + 1);
}
}
stable_sort(ve.begin(), ve.end());
vals[node].push_back({mx[ve[0]], ve[0]});
mx[ve[0]] = -1;
for(int i = 1; i < ve.size(); i++)
{
if(ve[i] != ve[i - 1])
{
vals[node].push_back({mx[ve[i]], ve[i]});
mx[ve[i]] = -1;
}
}
stable_sort(vals[node].rbegin(), vals[node].rend());
while(vals[node].size() > block)vals[node].pop_back();
}
inline void solve2()
{
for(int i = 1; i <= n; i++)
is[i] = false;
for(int i = 1; i <= y; i++)
{
int a; cin >> a;
is[a] = true;
}
int ptr = 0;
while(ptr < vals[x].size() && is[vals[x][ptr].second])ptr++;
if(ptr == vals[x].size())cout << -1 << endl;
else cout << vals[x][ptr].first << endl;
}
signed main()
{
cin >> n >> m >> q;
for(int i = 1; i <= m; i++)
{
int x, y; cin >> x >> y;
v[x].push_back(y);
v1[y].push_back(x);
}
for(int i = 1; i <= n; i++)
if(vals[i].empty())dfs(i);
while(q--)
{
cin >> x >> y;
if(y >= block)
solve1();
else
solve2();
}
return 0;
}
