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

N, K, S, T = map(int, input().split())
A = []
for i in range(N):
    A.append(tuple(map(int, input().split())))
A.sort()

F = [0] + sorted(list(map(int, input().split()))) + [S]

for machine in A:
    cost, v = machine
    t = 0
    for i in range(1, K + 2):
        dist = F[i] - F[i - 1]
        if v < dist:
            t += 2 * T + 1
        double = min(v-dist,dist)
        single = dist - double
        t += 2*single + double
    if t <= T:
        print(cost)
        exit()
