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 can(vi,gl,k,time,s):
    tc=0
    s=0;
    for g in gl:
        if 2*(g-s)<=vi:
            t=g-s;
        elif g-s<=vi:       
            t = 3*(g-s)-vi;
        else:
            return 0;
        s=g;
        tc+=t;
    return [0,1][tc<=time];
def binsearch(cv,l,r,gl,k,t,s):
    L,R = l,r;
    while l<=r:        
        median = (l+r)//2;
        cs=can(cv[median][1],gl,k,t,s);
        if cs==1:
            r=median-1;
            if r-l<=1:
                return median;
        else:
            l=median+1;
        
    return -1;
  
    

n,k,s,t = map(int, input().split());
cv = [];
gl = [];
for i in range(n):
    cv+=[list(map(int, input().split()))];
gl=sorted(list(map(int, input().split())));
if gl[k-1]<s:
    gl+=[s]
    k+=1
cv.sort(key=lambda x:x[0]);



index=binsearch(cv, 0, n-1, gl,k,t,s);
if index==-1:
    print(-1);
else:
    print(cv[index][0]);
