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 C {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int k = sc.nextInt();
		int s = sc.nextInt();
		int t = sc.nextInt();
		int cars[][] = new int[2][n];
		for (int i = 0; i < n; i++) {
			cars[0][i] = sc.nextInt();
			cars[1][i] = sc.nextInt();
		}
		int stations[] = new int[k + 1];
		for (int i = 0; i < k; i++) {
			stations[i] = sc.nextInt();
		}
		stations[k] = s;
		Arrays.sort(stations);
		long lo = 0;
		long mid, hi = (long) 1e9;
		while (lo + 1 < hi) {
			mid = (lo + hi) >> 1;
			if (canGo(mid, stations, s, t)) {
				hi = mid;
			} else {
				lo = mid;
			}
		}
		long ans = (long) 1e10;
		for (int i = 0; i < n; i++) {
			if (cars[1][i] >= hi) {
				ans = Math.min(ans, cars[0][i]);
			}
		}
		System.out.println(ans < ((long) 1e10) ? ans : -1);
	}

	static boolean canGo(long gas, int[] stations, int totalDist, int T) {
		int currentPos = 0;
		int nextStInd = 0;
		long totalTime = 0;
		while (nextStInd < stations.length) {
			long time = calcTime(gas, stations[nextStInd] - currentPos);
			if (time == -1)
				return false;
			totalTime += time;
			currentPos = stations[nextStInd];
			nextStInd++;
		}
		return totalTime <= T;
	}

	private static long calcTime(long gas, int dist) {
		if (gas < dist)
			return -1;
		long lo = 0;
		long mid, hi = gas >> 1;
		while (lo + 1 < hi) {
			mid = (lo + hi) >> 1;
			if (mid + (gas - (mid * 2L)) >= dist) {
				lo = mid;
			} else {
				hi = mid;
			}
		}
		return lo + ((dist - lo) * 2L);
	}
}
