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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class C {


    public static void main(String[] args) {

        MyScanner in = new MyScanner();

        int n = in.nextInt();
        int k = in.nextInt();
        int s = in.nextInt();
        int t = in.nextInt();

        int[][] cars = new int[n][2];
        for (int i = 0; i < n; ++i) {
            cars[i][0] = in.nextInt();
            cars[i][1] = in.nextInt();
        }

        int[] pos = new int[k];
        for (int i = 0; i < k; ++i) {
            pos[i] = in.nextInt();
        }

        Arrays.sort(pos);
        int low = 0;
        int high = 1000_000_000;

        while (low + 1 < high) {
            int mid = (low + high) / 2;
            if (f(pos, mid, t, s)) {
                high = mid;
            } else {
                low = mid;
            }
        }

        int minPrice = Integer.MAX_VALUE;
        for(int i=0;i<n;++i){
            if(cars[i][1]>=high){
                minPrice = Math.min(minPrice,cars[i][0]);
            }
        }

        if(minPrice==Integer.MAX_VALUE){
            System.out.println(-1);
        }else{
            System.out.println(minPrice);
        }
    }

    private static boolean f(int[] pos, int v, int t, int s) {
        int currX = 0;
        int nextStation = 0;
        int currTime = 0;
        while(currX<s){
            if(nextStation<pos.length && pos[nextStation]<s){
                int distance = pos[nextStation] - currX;
                if(minTime(distance,v)==-1){
                    return false;
                }
                currTime += minTime(distance,v);
                nextStation++;
                currX+=distance;
            }else{
                int distance = s - currX;
                if(minTime(distance,v)==-1){
                    return false;
                }
                currTime += minTime(distance,v);
                currX+=distance;
            }
        }
//        if(currTime<=t){
//            System.out.println(" V "+v);
//        }
        return currTime<=t;
    }

    private static int minTime(int distance, int v) {
        if(v<distance){
            return -1;
        }
        int delta = v-distance;
        if(delta>=distance){
            return distance;
        }
        return delta + (distance - delta) * 2;
    }

    // -----------MyScanner class for faster input----------
    public static class MyScanner {
        BufferedReader br;
        StringTokenizer st;

        public MyScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

    }
    // --------------------------------------------------------

}