program cojs155;
const
  dx:array[1..4]of longint=(1,-1,0,0);
  dy:array[1..4]of longint=(0,0,1,-1);
type
  qnode=record
    x,y:longint;
  end;
var
  q:array[1..10010]of qnode;
  a:array[0..110,0..110]of boolean;
  ans,n,m,k,i,j,x,y:longint;

procedure bfs(x,y:longint);
var
  xx,yy,i,front,tail:longint;
begin
  fillchar(q,sizeof(q),0);
  front:=0; tail:=1;
  q[1].x:=x; q[1].y:=y; a[x,y]:=false;
  while front<>tail do
  begin
    inc(front);
    for i:=1 to 4 do
    begin
      xx:=q[front].x+dx[i]; yy:=q[front].y+dy[i];
      if a[xx,yy] then
      begin
        inc(tail);
        q[tail].x:=xx;
        q[tail].y:=yy;
        a[xx,yy]:=false;
      end;
    end;
  end;
  if tail>ans then ans:=tail;
end;

begin
assign(input,'lake.in');reset(input);
assign(output,'lake.out');rewrite(output);

  readln(n,m,k);
  fillchar(a,sizeof(a),false);
  for i:=1 to k do
  begin
    readln(x,y);
    a[x,y]:=true;
  end;
  ans:=0;
  for i:=1 to n do
  for j:=1 to m do
    if a[i,j] then bfs(i,j);
  writeln(ans);

close(input);close(output);
end.