import sys
input = sys.stdin.buffer.readline
n,k,p = map(int,input().split())
a = list(map(int,input().split()))
b = list(map(int,input().split()))
c = [0]*p
for i in range(n):
	c[b[i]] += 1
for i in range(p-1):
	c[i+1] += c[i]
l,r = -1,p
while r-l>1:
	m = (l+r)//2
	cnt = 0
	for i in range(n):
		cnt += c[min(p-1,m+p-a[i]-1)]-c[p-a[i]-1]
		if m>=a[i]+1: cnt += c[m-a[i]-1]
	if cnt<k: l = m
	else: r = m
print(l)