import sys
input = lambda: sys.stdin.readline().strip()
import bisect
N,K,P = map(int,input().split())
A = list(map(int,input().split()))
B = list(map(int,input().split()))

R = [0 for i in range(P)]
for a in A:
  R[a] += 1
for i in range(P-1):
  R[i+1] += R[i]

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
    if m - b >= 0:
      res += R[m-b]
    x = min(P + m - b,P - 1)
    res += (R[x] - R[P-1-b])
  if res < K:
    l = m
  else:
    r = m
print(r)