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 sys
f = sys.stdin.readline
n,k,s,t = map(int, f().strip().split())
cost = []
cap = []
for i in range(n):
    c, v = map(int, f().strip().split())
    cost.append(c)
    cap.append(v)
gas = [int(v) for v in f().strip().split()]
gas.sort()
gas = [0] + gas + [s]

def util(fuel):
    ti = 0
    global t,k
    for i in range(1, k+2):
        dis = gas[i]-gas[i-1]
        if dis > fuel:
            return False
        ti += max(dis, 2*dis-min(dis, fuel-dis))
    if ti<=t:
        return True
    return False

l = 0
r = s
ans = 10**20
while l < r:
    mid = (l+r)//2
    if util(mid):
        r = mid
    else:
        l = mid + 1

if util(l):
    for i in range(n):
        if cap[i] >= l and ans > cost[i]:
            ans = cost[i]
    print(ans)
else:
    print(-1)