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 check(x):
    s=0
    l=0
    for i in range(k+1):
        d=b[i]-l
        if x-d<0:
            s=t+1
            break
        if 2*d<=x:
            s+=d
        else:
            x1=x-d
            y1=d-x1
            s+=(x1+2*y1)
        l=b[i]
        if s>t:
            break
    if s<=t:
        return True
    else:
        return False
    
def bs(r):
    ll=1
    while r>ll:
        m=(r+ll)/2
        if check(m):
            r=m-1
        else:
            ll=m+1
    return ll

n,k,s,t=[int(x) for x in raw_input().split()]
a=[]
r=0
for i in range(n):
    a.append([int(x) for x in raw_input().split()])
    r=max(r,a[-1][1])
b=[int(x) for x in raw_input().split()]
b.sort()
b.append(s)
a.sort()
mv=bs(r+4)
#print mv
ans=10**18
for i in range(n):
    if a[i][1]>=mv:
        ans=min(ans,a[i][0])
if ans==10**18:
    print -1
else:
    print ans
    
    
