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.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.Scanner;

public class A {
    int n, k, s, t;
    int[] c;
    int[] v;
    int[] g;
    long INF = (long)1e9 + 1;
    double minTime(int d, int v) {
        int b = 2 * d - v;
        if (b < 0) b = 0;
        if (b > d) return INF;
        return b + d; //(d - b) + b * 2;
    }

    boolean canRun(int v) {
        double minTime = 0;
        for (int i = 0; i < k + 1; i++) {
            minTime += minTime(g[i + 1] - g[i], v);
        }

//        System.out.println(v + " => " + minTime);
        return (minTime <= t + 0.1);
    }

    int minVolume() {
        int v0 = 1;
        int v1 = (int)1e9;

        while (v1 - v0 >= 3) {
            int m = (v0 + v1) / 2;

            if (canRun(m)) {
                v1 = m;
            } else {
                v0 = m + 1;
            }
        }

        for (int v = v0; v <= v1; v++) {
            if (canRun(v)) {
                return v;
            }
        }

        throw new RuntimeException();
    }

    public void run() throws FileNotFoundException {
//        Scanner sc = new Scanner(new File("A.txt"));
        Scanner sc = new Scanner(System.in);

        n = sc.nextInt();
        k = sc.nextInt();
        s = sc.nextInt();
        t = sc.nextInt();

        c = new int[n];
        v = new int[n];

        for (int i = 0; i < n; i++) {
            c[i] = sc.nextInt();
            v[i] = sc.nextInt();
        }

        g = new int[k + 2];
        g[0] = 0;
        for (int i = 1; i < k + 1; i++) {
            g[i] = sc.nextInt();
        }
        g[k + 1] = s;
        Arrays.sort(g);

        int minVolume = minVolume();
        int minCost = -1;
        for (int i = 0; i < n; i++) {
            if (v[i] >= minVolume) {
                if (minCost == -1 || c[i] < minCost) {
                    minCost = c[i];
                }
            }
        }

        System.out.println(minCost);
    }

    public static void main(String[] args) throws FileNotFoundException {
        new A().run();
    }
}
