#include <iostream>
#include <vector>
#include <queue>
using namespace std;
vector<int> graph[1000010];
bool visited[1000010];
int main() {
    int n;
    cin >> n;
    int b1,b2,p;
    cin >> b1 >> b2 >> p;
    int a[100010];
    int b[100010];
    for(int i=0;i<b1;i++){
        cin >> a[i];
    }
    for(int i =0;i<b2;i++){
        cin >> b[i];
    }
    int m;
    cin >> m;
    for(int i = 0;i<m;i++) {
        int r, l;
        cin >> r >> l;
        graph[r].push_back(l);
        graph[l].push_back(r);
    }


    for (int i = 0; i <=n ; i++) {
        visited[i] = false;
    }
    for(int i=0;i<b1;i++){
        visited[a[i]] = true;
    }
    for(int i =0;i<b2;i++){
        visited[b[i]] = true;
    }
    queue<int> q;
    int gradovi = 0;
    for(int i=0;i<b1;i++){
        q.push(a[i]);
        while(!q.empty()){
            int tocka = q.front();
            q.pop();
            for(int j = 0;j<graph[tocka].size();j++){
                int sosed = graph [tocka][j];
                if(!visited[sosed]){
                    visited[sosed] = true;
                    q.push(sosed);
                    gradovi++;
                }
            }
        }
    }
    if(gradovi > p) {
        gradovi = p;
    }
    cout << gradovi << endl;

}