import bisect
N,K,P = map(int,input().split())
A = list(map(int,input().split()))
B = list(map(int,input().split()))
A.sort()
B.sort()

l = -1
r = P - 1
while r - l > 1:
  m = (l + r) // 2
  res = 0
  for b in B:
    # a + b は 0 ~ 2*P - 1. m,m+P
    c = bisect.bisect_right(A,m-b)
    res += c
    c = bisect.bisect_right(A,m+P-b) - bisect.bisect_right(A,P-1-b)
    res += c
  if res < K:
    l = m
  else:
    r = m
print(r)