def lower_bound(a,x):
	ng,ok = -1,len(a)
	while ok-ng>1:
		m = (ng+ok)//2
		if x<=a[m]: ok = m
		else: ng = m
	return ok

def upper_bound(a,x):
	ok,ng = -1,len(a)
	while ng-ok>1:
		m = (ng+ok)//2
		if x>a[m]: ok = m
		else: ng = m
	return ok

n,k,p = map(int,input().split())
a = list(map(int,input().split()))
b = list(map(int,input().split()))
b.sort()
l,r = -1,p
while r-l>1:
	m = (l+r)//2
	cnt = 0
	for i in range(n):
		cnt += upper_bound(b,m+p-a[i])-lower_bound(b,p-a[i])+1+upper_bound(b,m-a[i])+1
	if cnt<k: l = m
	else: r = m
print(l)