#include <iostream>
#include <queue>
#include <vector>
using namespace std;
const int maxn = 100005;
vector<int> graph[maxn];
int main()
{
    int n, b1, b2, paricki;
    cin >> n >> b1 >> b2 >> paricki;

    vector<int> kosta(b1);
    vector<int> kiril(b2);

    vector<bool> visited(n, false);
    queue<int> q;
    for(int i = 0; i < b1; i++) {
        cin >> kosta[i];
        kosta[i]--;
        visited[kosta[i]] = true;
        q.push(kosta[i]);
    }

    for(int i = 0; i < b2; i++) {
        cin >> kiril[i];
        kiril[i]--;
        visited[kiril[i]] = true;
    }

    int m;
    cin >> m;
    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);
    }
    int res = 0;
    while(!q.empty()) {
        int c = q.front();
        q.pop();

        for(int i = 0; i < (int) graph[c].size(); i++) {
            int neighbour = graph[c][i];
            if(!visited[neighbour] and paricki > 0) {
                q.push(neighbour);
                paricki--;
                visited[neighbour] = true;
                res++;
            }
        }
    }
    cout << res << endl;

    return 0;
}