import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
sys.setrecursionlimit(10**7)
yes = lambda :print("yes");Yes = lambda :print("Yes")
no = lambda :print("no");No = lambda :print("No")
#######################################################################

N, K, P = na()

A = sorted(na())[::-1]
B = sorted(na())
B = B+[i+P for i in B]+[10*P]


def f(x):
    l = -1
    r = -1
    res = 0
    for i in range(N):
        while B[l+1]<=P-A[i]-1:
            l+=1
        while B[r+1]<=P+x-A[i]:
            r+=1
        res+=r-l
        #print(x,r,l)
    #print(x,res)
    return res>=K


ok = P-1
ng = -1
while ok-ng>1:
    d = (ok+ng)//2
    if f(d):
        ok = d
    else:
        ng = d

print(ok)