#include<bits/stdc++.h>
#define endl '\n'
#define X first
#define Y second
void speed()
{
std::ios_base::sync_with_stdio(0);
std::cin.tie(0);
std::cout.tie(0);
}
const int maxn=1e5+10,sq=100;
int n,m,q,x,y;
int dp[maxn];
std::vector<int> v[maxn],v1[maxn];
std::vector<std::pair<int,int>> s[maxn],s1[maxn];
bool used[maxn],banned[maxn],can[maxn];
bool cmp1(std::pair<int,int> p1,std::pair<int,int> p2)
{
if(p1.Y==p2.Y)
{
return p1.X<p2.X;
}
return p1.Y<p2.Y;
}
inline void read()
{
std::cin>>n>>m>>q;
int x1,y1;
for(int i=1; i<=m; i++)
{
std::cin>>x1>>y1;
v[x1].push_back(y1);
v1[y1].push_back(x1);
}
}
inline void dfs(int i)
{
used[i]=1;
for(auto nb:v[i])
{
if(used[nb]==0)
{
dfs(nb);
}
if(can[nb]==1)
{
dp[i]=std::max(dp[i],dp[nb]+1);
can[i]=1;
}
}
}
inline int small(int x,int y)
{
for(int i=1; i<=n; i++)
{
used[i]=banned[i]=dp[i]=can[i]=0;
}
can[x]=1;
for(int i=x; i>=1; i--)
{
if(used[i]==0)
{
dfs(i);
}
}
int node;
for(int i=1; i<=y; i++)
{
std::cin>>node;
banned[node]=1;
}
int ans=-1;
for(int i=1; i<=x; i++)
{
if(banned[i]==1||can[i]==0)
{
continue;
}
ans=std::max(ans,dp[i]);
}
if(ans==0&&banned[x]==1)
{
return -1;
}
return ans;
}
inline void dfs1(int i)
{
used[i]=1;
s[i].push_back({0,i});
for(auto nb:v1[i])
{
if(used[nb]==0)
{
dfs1(nb);
}
for(auto j:s1[nb])
{
s[i].push_back({j.X+1,j.Y});
}
}
sort(s[i].begin(),s[i].end(),cmp1);
for(int j=0;j<s[i].size();)
{
if(j<s[i].size()-1)
{
while(j<s[i].size()&&s[i][j].Y==s[i][j+1].Y)
{
j++;
}
}
s1[i].push_back(s[i][j]);
j++;
}
sort(s1[i].rbegin(),s1[i].rend());
while(s1[i].size()>sq+1)
{
s1[i].pop_back();
}
}
inline int large(int x,int y)
{
for(int i=1; i<=n; i++)
{
banned[i]=0;
}
int node;
for(int i=1;i<=y;i++)
{
std::cin>>node;
banned[node]=1;
}
for(auto j:s1[x])
{
if(banned[j.Y]==0)
{
return j.X;
}
}
return -1;
}
int main()
{
speed();
read();
for(int i=1;i<=n;i++)
{
if(used[i]==0)
{
dfs1(i);
}
}
int x,y;
for(int i=1;i<=q;i++)
{
std::cin>>x>>y;
if(y>sq)
{
std::cout<<small(x,y)<<endl;
}
else
{
std::cout<<large(x,y)<<endl;
}
}
return 0;
}
