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, raw_input().split(' '))
car=[map(int, raw_input().split(' ')) for _ in xrange(n)]
d=[0]+map(int, raw_input().split(' '))+[s]
d.sort()
def custom_cmp(a,b):
	if a[1]<b[1]:
		return -1
	elif a[1]==b[1]:
		if a[0]<b[0]:
			return -1
		else:
			return 1
	else:
		return 1
def can(w):
	t=0
	for i in xrange(1,len(d)):
		dist=d[i]-d[i-1]
		if dist>w:
			return False
		a=min(w/2,w-dist)
		t+=a+2*(dist-a)
	if t<= T :
		return True
	else:
		return False 

car.sort(custom_cmp)
# print car

# print can(car[1][1])
lo=0
hi=n-1
while(lo<hi):
	mid=lo + (hi-lo)/2
	if can(car[mid][1]):
		hi=mid
	else:
		lo=mid+1

if can(car[hi][1]):
	print car[hi][0]
else:
	print -1




