import java.util.*; import java.io.*; public class Main { static final int INF = 1<<30; static final long INFL = 1L<<60; static final int MOD = 1000000007; static final int MOD2 = 998244353; static List> g; public static void main(String[] args) { FastScanner fs = new FastScanner(); PrintWriter pw = new PrintWriter(System.out); int n = fs.nextInt(); long k = fs.nextLong(); int p = fs.nextInt(); int[] a = fs.nextInts(n); int[] b = fs.nextInts(n); Arrays.sort(b); int left = 0, right = p; //mid以下の数値がk個以上あるmidの最小値 while(right-left > 1){ int mid = (right+left) / 2; int cnt = 0; for(int i = 0; i < n; i++){ int tar = p-a[i]; int l = -1, r = n; while(r-l > 1){ int m = (r+l) / 2; if(tar <= b[m]) r = m; else l = m; } int l1 = -1, r1 = l+1; while(r1-l1 > 1){ int m1 = (r1+l1) / 2; if(mid < b[m1]+a[i]) r1 = m1; else l1 = m1; } cnt += r1; int l2 = r-1, r2 = n; while(r2-l2 > 1){ int m2 = (r2+l2) / 2; if(mid < (b[m2]+a[i])%p) r2 = m2; else l2 = m2; } cnt += r2-r; } if(k <= cnt) right = mid; else left = mid; } pw.println(right); pw.close(); } } class FastScanner { private InputStream in = System.in; private byte[] buffer = new byte[1024]; private int length = 0, p = 0; private boolean hasNextByte() { if (p < length) return true; else{ p = 0; try{ length = in.read(buffer); }catch(Exception e){ e.printStackTrace(); } if(length == 0) return false; } return true; } private int readByte() { if (hasNextByte() == true) return buffer[p++]; return -1; } private static boolean isPrintable(int n) { return 33 <= n && n <= 126; } private void skip() { while (hasNextByte() && !isPrintable(buffer[p])) p++; } public boolean hasNext() { skip(); return hasNextByte(); } public String next() { if(!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int temp = readByte(); while (isPrintable(temp)) { sb.appendCodePoint(temp); temp = readByte(); } return sb.toString(); } public int nextInt() { return Math.toIntExact(nextLong()); } public int[] nextInts(int n) { int[] ar = new int[n]; for (int i = 0; i < n; i++) ar[i] = nextInt(); return ar; } public long[] nextLongs(int n) { long[] ar = new long[n]; for (int i = 0; i < n; i++) ar[i] = nextLong(); return ar; } public long nextLong() { if(!hasNext()) throw new NoSuchElementException(); boolean minus = false; int temp = readByte(); if (temp == '-') { minus = true; temp = readByte(); } if (temp < '0' || '9' < temp) throw new NumberFormatException(); long n = 0; while (isPrintable(temp)) { if ('0' <= temp && temp <= '9') { n *= 10; n += temp - '0'; } temp = readByte(); } return minus ? -n : n; } public char[] nextChars() { String s = next(); return s.toCharArray(); } public char[][] nextCharMat(int h, int w) { char[][] ar = new char[h][w]; for(int i = 0; i < h; i++){ String s = next(); for(int j = 0; j < w; j++){ ar[i][j] = s.charAt(j); } } return ar; } }