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

def check(n):
    count = 0
    for i in A:
        left = bisect.bisect_left(B, P-i)
        right = bisect.bisect_right(B, n+P-i)
        count += right - left

        right2 = bisect.bisect_right(B, n-i)
        count += right2
    return count >= K

ng,ok = -1,P-1
while(ok - ng > 1):
    mid = (ok+ng)//2
    if(check(mid)):
        ok = mid
    else:
        ng = mid
print(ok)