#include <iostream>

#include <cstdio>

#include <sstream>

#include <cstring>

#include <map>

#include <cctype>

#include <set>

#include <vector>

#include <stack>

#include <queue>

#include <algorithm>

#include <cmath>

#include <bitset>

#define rap(i, a, n) for(int i=a; i<=n; i++)

#define rep(i, a, n) for(int i=a; i<n; i++)

#define lap(i, a, n) for(int i=n; i>=a; i--)

#define lep(i, a, n) for(int i=n; i>a; i--)

#define rd(a) scanf("%d", &a)

#define rlld(a) scanf("%lld", &a)

#define rc(a) scanf("%c", &a)

#define rs(a) scanf("%s", a)

#define pd(a) printf("%d\n", a);

#define plld(a) printf("%lld\n", a);

#define pc(a) printf("%c\n", a);

#define ps(a) printf("%s\n", a);

#define MOD 2018

#define LL long long

#define ULL unsigned long long

#define Pair pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define _  ios_base::sync_with_stdio(0),cin.tie(0)

//freopen("1.txt", "r", stdin);

using namespace std;

const int maxn = , INF = 0x7fffffff, LL_INF = 0x7fffffffffffffff;

int n, m, z, s, t, cnt, p;

int f[maxn], re[][];

int d[maxn], cur[maxn], head[maxn];

struct node

{

    int u, v, c, next;

}Node[maxn << ];

void add_(int u, int v, int c)

{

    Node[cnt].u = u;

    Node[cnt].v = v;

    Node[cnt].c = c;

    Node[cnt].next = head[u];

    head[u] = cnt++;

}

void add(int u, int v, int c)

{

    add_(u, v, c);

    add_(v, u, );

}

bool bfs()

{

    queue<int> Q;

    mem(d, );

    Q.push(s);

    d[s] = ;

    while(!Q.empty())

    {

        int u = Q.front(); Q.pop();

        for(int i = head[u]; i != -; i = Node[i].next)

        {

            node e = Node[i];

            if(!d[e.v] && e.c > )

            {

                d[e.v] = d[u] + ;

                Q.push(e.v);

                if(e.v == t) return ;

            }

        }

    }

    return d[t] != ;

}

int dfs(int u, int cap)

{

    int ret = ;

    if(u == t || cap == )

        return cap;

    for(int &i = cur[u]; i != -; i = Node[i].next)

    {

        node e = Node[i];

        if(d[e.v] == d[u] +  && e.c > )

        {

            int V = dfs(e.v, min(cap, e.c));

            Node[i].c -= V;

            Node[i ^ ].c += V;

            ret += V;

            cap -= V;

            if(cap == ) break;

        }

    }

    if(cap > ) d[u] = -;

    return ret;

}

int Dinic()

{

    int ans = ;

    while(bfs())

    {

        memcpy(cur, head, sizeof(head));

        ans += dfs(s, INF);

    }

    return ans;

}

int find(int x)

{

    return f[x] == x ? x : (f[x] = find(f[x]));

}

void build(int mid)

{

    for(int i = ; i <= n; i++)

    {

        add(s, i, mid);

        add(n + i, t, mid);

        add(i, n *  + i, p);

    }

    for(int i = ; i <= n; i++)

        for(int k = n + ; k <= n * ; k++)

        {

            if(re[i][k]) add(i, k, );

            else add(n *  + i, k, );

        }

}

void init()

{

    for(int i = ; i < maxn; i++) f[i] = i;

    mem(re, );

    mem(head, -);

    cnt = ;

}

int main()

{

    int T;

    rd(T);

    while(T--)

    {

        init();

        int a, b;

        rd(n), rd(m), rd(p), rd(z);

        s = , t = n *  + ;

        for(int i = ; i < m; i++)

        {

            rd(a), rd(b);

            b += n;

            re[a][b] = re[b][a] = ;

        }

        for(int i = ; i < z; i++)

        {

            rd(a), rd(b);

            int r = find(a);

            int l = find(b);

            if(r != l) f[l] = r;

        }

        for(int i = ; i <= n; i++)

        {

            for(int j = i + ; j <= n; j++)

            {

                if(find(i) == find(j))

                    for(int k = n + ; k <= n * ; k++)

                        re[i][k] = re[j][k] = (re[i][k] || re[j][k]);

            }

        }

        int x = , y = ;

        while(x <= y)

        {

            mem(head, -);

            cnt = ;

            int mid = x + (y - x) / ;

            build(mid);

            if(Dinic() == mid * n) x = mid + ;

            else y = mid - ;

        }

        pd(y);

    }

    return ;

}