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

A.sort()
B.sort()


dic = {}
dic[-1] = 0
suma = 1
def check_o(n):
    x = bisect.bisect_left(A, n)
    y = bisect.bisect_right(A, n)
    if x != y:
        return x
    else: 
        return x - 1     

A2 = []
for a in A:
    dic[a] = suma
    dic[P + a] = N + suma
    suma += 1
    A2.append(P + a)
A = [-1] + A + A2
#print(A)
#print(dic)

def check(T):
    num = 0
    for b in B:
        x = check_o(P+T-b)
        y = check_o(P-b-1)
        
        num += dic[A[x]] - dic[A[y]]
        #print(b,P+T-b,A[x],P-b-1,A[y])
    #print(T,num)
    return (num < K)

lb = 0 
ub = P
    
while ub - lb > 1:
    mid = (ub + lb) // 2
    if check(mid):
        lb = mid
    else:
        ub = mid
print(lb+1)