N,K,P = map(int,input().split())
A = list(map(int,input().split()))
B = list(map(int,input().split()))
A.sort()
B.sort()
from collections import Counter
c = Counter(B)
F = [0]*(P+1)
for i in range(1,P):
    F[i+1] = F[i] + c[i]
def is_ok(x):
    tmp = 0
    for a in A:
        if 0<=x-a<=P-1:
            tmp += F[x-a+1] - F[0]
            
        if P-a <= P-1:
            tmp += F[min(P-1,P+x-a)+1] - F[P-a]
        
    return tmp >= K
            
            
y = 2*P
x = -1
while y-x>1:
    mid = (y+x)//2
    
    if is_ok(mid):
        y = mid
    else:
        x = mid
print(y)