import java.util.Arrays;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = Integer.parseInt(sc.next());
		long K = Long.parseLong(sc.next());
		int P = Integer.parseInt(sc.next());
		int[] A = new int[N];
		for ( int i = 0 ; i < N ; i++ ) {
			A[i] = Integer.parseInt(sc.next());
		}
		int[] B = new int[N];
		for ( int i = 0 ; i < N ; i++ ) {
			B[i] = Integer.parseInt(sc.next());
		}
		sc.close();

		Arrays.sort(B);
		
		int min = 0;
		int max = P - 1;
		while ( max - min > 1 ) {
			int mid = (min + max) / 2;
			if ( count(A, B, mid, P) < K ) {
				min = mid;
			} else {
				max = mid;
			}
		}
		
		System.out.println(min);
	}
	
	static long count(int[] A, int[] B, int x, int P) {
		long cnt = 0;
		for ( int a : A ) {
			// 0 == x,  P == x + P
			cnt += count(B, x - a);
			cnt += count(B, x + P - a) - count(B, P - a);
		}
		return cnt;
	}
	static long count(int[] B, int x) {
		if ( B[0] >= x ) {
			return 0;
		} else if ( B[B.length - 1] < x ) {
			return B.length;
		}
		int min = 0;
		int max = B.length - 1;
		while ( max - min > 1 ) {
			int mid = (min + max) / 2;
			if ( B[mid] < x ) {
				min = mid;
			} else {
				max = mid;
			}
		}
		return min + 1;
	}
}