#include<bits/stdc++.h>
using namespace std;
const int maxn=100000+5,maxm=200000+5,sq=sqrt(100000+5);
int n,m,q;
vector<int>adj[maxn];
int fp[maxn];
deque<pair<int,int>>res[maxn];
void merge(int u,int v){
for(auto x:res[u]){
fp[x.first]=1;
}
for(auto x:res[v]){
fp[x.first]=1;
}
deque<pair<int,int>>fake;
int cnt=0;
int ii=res[u].size()-1,jj=res[v].size()-1;
while(cnt<=sq&&!(ii<0&&jj<0)){
pair<int,int>x;
if(ii<0){
x=res[v][jj];
jj--;
}
else if(jj<0){
x=res[u][ii];
x.second++;
ii--;
}
else if(res[u][ii].second+1>res[v][jj].second){
x=res[u][ii];
x.second++;
ii--;
}
else{
x=res[v][jj];
jj--;
}
if(fp[x.first]==0){
continue;
}
cnt++;
fp[x.first]=0;
fake.push_front(x);
}
res[v].swap(fake);
}
void pre(){
for(int i=1;i<=n;i++){
res[i].push_back(make_pair(i,0));
for(auto x:adj[i]){
merge(x,i);
}
}
}
int sqq[sq+2];
int solvel(int u,int v,int t){
int alliq[v];
for(int i=0;i<v;i++){
cin>>alliq[i];
for(int j=0;j<(int)res[u].size();j++){
if(res[u][j].first==alliq[i]){
sqq[j]=t;
break;
}
}
}
int jj=res[u].size()-1;
while(true){
if(jj==-1){
return -1;
}
if(sqq[jj]==t){
jj--;
continue;
}
return res[u][jj].second;
}
}
int solveh(int u,int v){
int all[v+1];
for(int i=0;i<v;i++){
cin>>all[i];
}
all[v]=n+2;
int j=0;
vector<int>dp(n+1,-1);
for(int i=1;i<=u;i++){
if(i==all[j]){
j++;
}
else{
dp[i]=0;
}
for(auto x:adj[i]){
if(dp[x]!=-1){
dp[i]=max(dp[x]+1,dp[i]);
}
}
}
return dp[u];
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>m>>q;
for(int i=0;i<m;i++){
int u,v;
cin>>u>>v;
adj[v].push_back(u);
}
pre();
for(int i=0;i<q;i++){
int u,v;
cin>>u>>v;
if(v<sq){
cout<<solvel(u,v,i+1)<<"\n";
}
else{
cout<<solveh(u,v)<<"\n";
}
}
}
