//
// Created by 刘宇韬 on 2022年2月25日.
//
#include "bits/stdc++.h"
using namespace std;
typedef long long LL;
const int N = 205,M = N*N;
typedef pair<int,int> PII;
#define x first
#define y second
int h[N],e[M],ne[M],idx;
int dis[N][N];
void add(int a,int b){
 e[idx] = b;
 ne[idx] = h[a];
 h[a] = idx++;
}
PII p[N];
int n,m,k,r;

bool check(PII a, PII b)
{

 LL dx = a.x - b.x;
 LL dy = a.y - b.y;
 return dx * dx + dy * dy <= (LL)r * r;
}
int bfs(){
 queue<PII> q;
 memset(dis,0x3f,sizeof dis);
 dis[1][0] = 0;
 //队列里放的是{点编号,截止目前用的路由器的数量}
 q.push({1,0});
 while (!q.empty()){
 auto t = q.front();
 q.pop();
 for(int i = h[t.x]; ~i; i = ne[i]) {
 int j = e[i],cnt = t.y;
 
 if (j>n)cnt++;
 if (cnt<=k){
 if (dis[j][cnt]>dis[t.x][t.y]+1){
 dis[j][cnt] = dis[t.x][t.y]+1;
 q.push({j,cnt});
 }
 }
 }
 }
 int res = 1e8;
 for(int i = 0; i <=k; i++) {
 res = min(res,dis[2][i]);
 }
 return res-1;
}

int main(){
 cin>>n>>m>>k>>r;
 memset(h,-1,sizeof h);
 for(int i = 1; i <=n+m; i++) {
 cin>>p[i].x>>p[i].y;
 }
 for(int i = 1; i <=n+m; i++) {
 for(int j = i+1; j <=n+m; j++) {
 if (check(p[i],p[j])){
 add(i,j);
 add(j,i);
 }
 }
 }
 cout<<bfs()<<endl;
}