from bisect import *
N,K,P=map(int,input().split())
A=list(map(int,input().split()))
A.sort()
B=list(map(int,input().split()))
B.sort()
L,R=0,P
while L<R:
  M=(L+R)>>1
  C=0
  for i in range(N):
    if M>=A[i]:
      C+=bisect_right(B,M-A[i])+bisect_right(B,P+M-A[i])-bisect_left(B,P-A[i])
    else:
      C+=bisect_right(B,P+M-A[i])-bisect_left(B,P-A[i])
  if C>=K:
    R=M
  else:
    L=max(L+1,M)
print(L)