using System; using System.Collections.Generic; using System.Linq; class G { static int[] Read() => Array.ConvertAll(Console.ReadLine().Split(), int.Parse); static (int, int) Read2() { var a = Read(); return (a[0], a[1]); } static long[] ReadL() => Array.ConvertAll(Console.ReadLine().Split(), long.Parse); static (long, long, long) Read3L() { var a = ReadL(); return (a[0], a[1], a[2]); } static void Main() => Console.WriteLine(Solve()); static object Solve() { var (n, k, p) = ((int, long, int))Read3L(); var a = Read(); var b = Read(); Array.Sort(b); b = b.Concat(b.Select(v => v + p)).ToArray(); return First(0, p, x => { // x までの個数 var c = 0L; foreach (var v in a) { var l = First(0, b.Length, i => v + b[i] >= p); var r = First(0, b.Length, i => v + b[i] > p + x); c += r - l; } return c >= k; }); } static int First(int l, int r, Func f) { int m; while (l < r) if (f(m = l + (r - l - 1) / 2)) r = m; else l = m + 1; return r; } }