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

def ii():
	return map(int,raw_input().split())

def check(val):
	time = 0
	for ele in petrol:
		if val >= 2*ele:
			time += ele
		elif val >= ele:
			time += 3*ele - val
		else:
			return 0
		if time > t:
			return 0

	return 1

n,k,s,t = ii()
lis = []
for _ in xrange(n):
	lis.append(ii())

petrol = ii()
petrol.sort()
petrol.append(s-petrol[-1])
for i in xrange(k-1,0,-1):
	petrol[i] -= petrol[i-1]

lo = 1
hi = 10**9 + 2
ans = 10**9 + 1
while (lo < hi):
	mid = (hi+lo)/2
	if check(mid):
		ans = mid
		hi = mid-1
	else:
		lo = mid+1

cost = 10**9 + 5
for c,p in lis:
	if p >= ans:
		cost = min(cost,c)

print cost