var
  n,m,k,i,a,b,ans,p,j:longint;
  f:array[0..100,0..100] of boolean;
 
 
procedure test(l,r:longint);
begin
  if f[l+1,r]=true then
  begin
    inc(p);
    f[l+1,r]:=false;
    test(l+1,r);
  end;
    if f[l,r+1]=true then
  begin
    inc(p);
    f[l,r+1]:=false;
    test(l,r+1);
  end;
   if f[l-1,r]=true then
  begin
    inc(p);
    f[l-1,r]:=false;
    test(l-1,r);
  end;
   if f[l,r-1]=true then
  begin
    inc(p);
    f[l,r-1]:=false;
    test(l,r-1);
  end;
end;
 
 
 

begin
   assign(input,'lake.in');
   assign(output,'lake.out');
   reset(input);rewrite(output);
   
   
  fillchar(f,sizeof(f),false);
  read(n,m,k);
  for i:=1 to k do 
  begin
    read(a,b);
    f[a,b]:=true;
  end;
  ans:=0;
  for j:=1 to m do
	for i:=1 to n do if f[i,j]=true then
	begin
	  p:=1;
	  f[i,j]:=false;
	  test(i,j);
	  if p>ans then ans:=p;
	end;
  writeln(ans);
  close(input);close(output);
end.