import java.util.HashSet;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;


public class Radio {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int R=in.nextInt();
		int S=in.nextInt();
		int N=in.nextInt();
		Stanica[] stanice = new Stanica[N+2];
		stanice[0]=new Stanica(0,0);
		for (int i=1;i<=N;i++) stanice[i]=new Stanica(in.nextInt(),in.nextInt());
		stanice[N+1]=new Stanica(R,S);


		int U=1000000000;
		int L=0;
		while(L<U){

		int probajRjesenje= (U+L)/2;
		int[][] veze = new int[N+2][N+2];
		for(int i=0;i<N+2;i++)
			for(int j=0;j<N+2;j++)
			{
				if (i==j) continue;
				 veze[i][j]=0;

			}



		for(int i=0;i<N+2;i++)
			for(int j=0;j<N+2;j++)
			{
				if (i==j) continue;
				if ((udaljenost(stanice[i],stanice[j])/2)<=probajRjesenje) veze[i][j]=1;

			}
		Queue<Integer> kju = new LinkedList<Integer>();
		kju.add(0);
		boolean moze=false;
		HashSet<Integer> vecbio = new HashSet<Integer>();

		while(true){
			if (kju.isEmpty()) break;
			int trenutni=kju.poll();
			vecbio.add(trenutni);
			if (trenutni==N+1) {moze=true; break;}
			for (int k=0;k<N+2;k++){
				if (veze[trenutni][k]==1) if (!vecbio.contains(k)) {kju.add(k); vecbio.add(k);}
			}

		}

		kju.clear();
		vecbio.clear();
		if (moze) U=probajRjesenje;
		else L=probajRjesenje+1;


		}
		System.out.println(L);
	}

	private static int udaljenost(Stanica a, Stanica b) {

		return Math.abs(a.r-b.r)+Math.abs(a.s-b.s);
	}

}



class Stanica{
	public int r;
	public int s;


	public Stanica() {
		// TODO Auto-generated constructor stub
	}

	public Stanica(int r, int s) {
		this.r=r;
		this.s=s;
	}







}