import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))


n,k,p = list(map(int, input().split()))
a = list(map(int, input().split()))
b = list(map(int, input().split()))
a.sort()
b.sort()
from bisect import bisect_left as bl, bisect_right as br
def sub(x):
    val = 0
    for i in range(n):
        v = a[i]
        ind = bl(b, p-v)
        i0 = br(b, x-v)
        i1 = br(b, x+p-v)
#         print(v, ind, i0, i1, x)
        if i0>0:
            val += min(i0, ind)
        if i1>=ind:
            val += (i1-ind)
#         if val>k:
#             return 0
    return val
l = -1
r = p+1
while abs(l-r)>1:
    m = (l+r)//2
    if sub(m)<k:
        l = m
    else:
        r = m
ans = r
print(ans)