#include <iostream>
#include <vector>
#include <queue>
using namespace std;
const int maxn = 1e5 + 10;

vector<int> graph[maxn];
int main() {
    int n, num_kiril, num_kosta, coins;
    cin >> n >> num_kosta >> num_kiril >> coins;

    vector<int> kiril(num_kiril);
    vector<int> kosta(num_kosta);

    vector<bool> visited(n, false);
    queue<int> q;
    for(int i = 0; i < num_kosta; i++) {
        cin >> kosta[i];
        kosta[i]--;
        q.push(kosta[i]);
        visited[kosta[i]] = true;
    }
    for(int i = 0; i < num_kiril; i++) {
        cin >> kiril[i];
        kiril[i]--;
        visited[kiril[i]] = true;
    }

    int m;
    cin >> m;
    int res = 0;
    for(int i = 0; i < m; i++) {
        int a, b;
        cin >>  a >> b;
        a--; b--;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    while(!q.empty()) {
        int node = q.front();
        q.pop();

        for(int i = 0; i < (int) graph[node].size(); i++) {
            int neighbour = graph[node][i];

            if(!visited[neighbour] and coins > 0) {
                visited[neighbour] = true;
                q.push(neighbour);
                coins--;
                res++;
            }
        }
    }
    cout << res << endl;



    return 0;
}