import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        long k = sc.nextLong();
        int p = sc.nextInt();
        int[] aArr = new int[n];
        for (int i = 0; i < n; i++) {
            aArr[i] = sc.nextInt() % p;
        }
        Arrays.sort(aArr);
        int[] bArr = new int[n];
        for (int i = 0; i < n; i++) {
            bArr[i] = sc.nextInt() % p;
        }
        Arrays.sort(bArr);
        int left = 0;
        int right = p;
        while (right - left > 1) {
            int m = (left + right) / 2;
            int one = n - 1;
            int zero = n - 1;
            int two = n - 1;
            long count = 0;
            for (int i = 0; i < n; i++) {
                while (one >= 0 && aArr[i] + bArr[one] >= m) {
                    one--;
                }
                count += one + 1;
                while (zero >= 0 && aArr[i] + bArr[zero] >= p) {
                    zero--;
                }
                while (two >= 0 && aArr[i] + bArr[two] >= p + m) {
                    two--;
                }
                count += two - zero;
            }
            if (count >= k) {
                right = m;
            } else {
                left = m;
            }
        }
        System.out.println(left);
    }
    
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}