/*
VENI VIDI VICI
*/
// #pragma GCC optimize("Ofast","unroll-all-loops","fast-math","no-stack-protector","give-no-fuck")
#include <bits/stdc++.h>
// #include <iostream>
// #include <vector>
// #include <algorithm>
// #include <set>
// #include <map>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define rep(i,x, n) for (int i = (x); i < (n); ++i)
#define repr(i,x, n) for (int i = (n) - 1; i >= (x); --i)
mt19937 RNG(chrono::steady_clock::now().time_since_epoch().count());
// #define sum accumulate
//using i128 = __int128;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vpi = vector<pair<int, int>>;
using vvi = vector<vi>;
using sll = set<ll>;
template<class T>
istream& operator>>(istream& is, vector<T>& v) {
for(auto &i:v) is>>i;
return is;
}
template<class T1,class T2>
istream& operator>>(istream& is, pair<T1,T2>& p) {
is>>p.fi>>p.se;
return is;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
for(const auto &i:v) os<<i<<' ';
return os;
}
template<class T1,class T2>
ostream& operator<<(ostream& os, const pair<T1,T2>& p) {
os<<p.fi<<' '<<p.se; return os;
}
void pyn(bool x)
{
cout<<(x?"YES":"NO")<<endl;
}
void pYN(bool x)
{
cout<<(x?"Yes":"No")<<endl;
}
void pAB(bool x)
{
cout<<(x?"Alice":"Bob")<<endl;
}
ll powmod(ll a,ll b,ll modulo)
{
if(b==0){
return 1;
}
ll temp=powmod(a,b/2,modulo);
if(b%2==0){
return (temp*temp)%modulo;
}
else{
return (a*((temp*temp)%modulo))%modulo;
}
}
bool Prime(ll n){
for (ll i = 2; i*i <= n; i++)
if (n % i == 0)
return false;
return (n>1);
}
void readIO() {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
}
void solve();
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// readIO();
int uwu=1;
// cin>>uwu;
for(int tc=1;tc<=uwu;tc++) {
// cout<<"Case #"<<tc<<": ";
solve();
}
return 0;
}
const int N=1e5+100;
vl ma[N],rma[N];
map<ll,ll> dist[N];
void solve()
{
ll n,m,q;
cin>>n>>m>>q;
for(int i=0;i<m;i++)
{
int s,e;
cin>>s>>e;
ma[s].pb(e);
rma[e].pb(s);
}
// if(q>1)
// {
// exit(-1);
// cout<<-1<<endl;
// return;
// }
int t,sz;
cin>>t>>sz;
vl ads(sz);
cin>>ads;
sll kill(all(ads));
for(int i=1;i<=n;i++)
{
for(auto x:rma[i])
{
for(auto y:dist[x])
{
dist[i][y.first]=max(dist[i][y.first],y.second+1);
}
dist[i][x]=max(dist[i][x],1ll);
}
}
ll mx=-1;
for(auto y:dist[t])
{
if(kill.find(y.first)!=kill.end())continue;
mx=max(mx,y.second);
}
cout<<mx<<endl;
}
