1 1 2 2
1000000000 1000000000
1
 1 1 1000000000 1000000000
100 1000000000
1
 1 1 10 18
5 6
5
 2 1 1000000000 2000000000
111 999999999
101 999999998
1
 4 13 400 600
13 30
1 19
1 160
1 113
58 73 15 319 194 362 128 157 336 162 77 90 96
 1 15 100 200
283 8
30 58 16 45 80 82 55 95 24 23 86 28 51 47 20
 3 2 300 400
24 68
13 65
15 113
127 177
 1 1 2 1
1 10
1
 4 2 7 15
10 9
4 4
9 3
4 10
1 6
 2 1 1000000000 2000000000
111 1000000000
101 1000000000
5
 2 1 1000000000 2000000000
111 999999998
101 999999998
1
 1 1 1000000000 1000000000
1 1000000000
1

1000000000
 -1
 5
 111
 1
 -1
 -1
 -1
 4
 101
 -1
 -1

import java.util.Arrays;
import java.util.Scanner;
public class ProgC {

	static int n,k,s,t;
	static int[] arr;
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		n=in.nextInt();
		k=in.nextInt();
		s=in.nextInt();
		t=in.nextInt();
		int[] cost = new int[n];
		int[] bak = new int[n];
		for(int i=0;i<n;i++) {
			cost[i]=in.nextInt();
			bak[i]=in.nextInt();
		}
		arr = new int[k+2];
		for(int j=1;j<=k;j++){
			arr[j]=in.nextInt();
		}
		arr[k+1]=s;
		arr[0]=0;
		Arrays.sort(arr);
		
		int point=s/2;
		int delta=s/2;
		while(delta>0) {
			if(point<0 | point>s)break;
			else if(can(point)) {
				if(!can(point-1)) {
					break;
				}
				delta=(delta+1)/2;
				point-=delta;
			}
			else {
				delta=(delta+1)/2;
				point+=delta;
			}
		}
		int id=-1;
		int mincost=2000000000;
		for(int i=0;i<n;i++) {
			if((cost[i]<mincost)&(bak[i]>=point)) {
				id=i;
				mincost=cost[i];
			}
		}
		if(id==-1)System.out.print(-1);
		else System.out.print(mincost);
	}
	
	static boolean can(int w) {
		int benzin = w;
		int time = t;
		for(int i=0;i<arr.length-1;i++) {
			benzin=w;
			if(time<0) return false;
			if(benzin>=2*(arr[i+1]-arr[i])) {
				time-=(arr[i+1]-arr[i]);
			}
			else if(benzin>(arr[i+1]-arr[i])) {
				//t-=(benzin-(arr[i+1]-arr[i]));
				//time-=2*((arr[i+1]-arr[i])-(benzin-(arr[i+1]-arr[i])));
				//time-=(benzin-(arr[i+1]-arr[i]));
				time-=(benzin-(arr[i+1]-arr[i]));
				benzin-=2*(benzin-(arr[i+1]-arr[i]));
				time-=2*benzin;
			}
			else if(benzin==(arr[i+1]-arr[i])) {
				time-=2*(arr[i+1]-arr[i]);
			}
			else return false;
		}
		if(time<0) return false;
		return true;
	}

}
