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

from itertools import izip

num_cars, num_gas_stations, cinema_pos, target_time = map(int, raw_input().split(' '))

cars = [tuple(map(int, raw_input().split(' '))) for _ in xrange(num_cars)]

gas_stations = map(int, raw_input().split(' '))

gas_stations.extend([0, cinema_pos])
gas_stations.sort()

l, r = 0, 10 ** 9

while l < r:
    cap = (l + r) / 2

    current_time = 0

    for prev, this in izip(gas_stations, gas_stations[1:]):
        if (this - prev) * 2 <= cap:
            current_time += this - prev
        elif this - prev <= cap:
            current_time += (this - prev) * 2
            current_time -= cap - (this - prev)
        else:
            current_time = None
            break

    if current_time is not None and current_time <= target_time:
        r = cap
    else:
        l = cap + 1

min_cost = 10 ** 9 + 1

min_cap = l

for cost, cap in cars:
    if cap >= min_cap and cost < min_cost:
        min_cost = cost
        break

if min_cost != 10 ** 9 + 1:
    print min_cost
else:
    print -1
