program caodituozhanwenti;
var
  c,x,t,y,mx,w,my,i,j:integer;
  bz:boolean;
  a:array[0..101,0..101]of integer;
  b:char;
begin
  assign (input,'milkweed.in');
  reset (input);
  assign (output,'milkweed.out');
  rewrite (output);
  readln (x,y,mx,my);
  for i:=1 to y do
  begin
    for j:=1 to x do
    begin
      read (b);
      if b='*' then
      begin
        a[i,j]:=0;
        w:=w+1
      end
      else
        a[i,j]:=-1
    end;
    readln
  end;
  a[mx,my]:=1;
  t:=t+1;
  repeat
    t:=t+1;
    bz:=true;
    for i:=1 to y do
      for j:=1 to x do
      if a[i,j]=t-1 then
        begin
          if a[i,j-1]=-1 then
          begin
            bz:=false;
            a[i,j-1]:=t
          end;
          if a[i,j+1]=-1 then
          begin
            bz:=false;
            a[i,j+1]:=t
          end;
          if a[i-1,j]=-1 then
          begin
            bz:=false;
            a[i-1,j]:=t
          end;
          if a[i+1,j]=-1 then
          begin
            bz:=false;
            a[i+1,j]:=t
          end;
          if a[i-1,j-1]=-1 then
          begin
            bz:=false;
            a[i-1,j-1]:=t
          end;
          if a[i-1,j+1]=-1 then
          begin
            bz:=false;
            a[i-1,j+1]:=t
          end;
          if a[i+1,j-1]=-1 then
          begin
            bz:=false;
            a[i+1,j-1]:=t
          end;
          if a[i+1,j+1]=-1 then
          begin
            bz:=false;
            a[i+1,j+1]:=t
          end
        end;
    if bz=true then
    begin
      writeln ('-1');
      close (input);
      close (output);
      halt
    end;
    c:=0;
    for i:=1 to y do
      for j:=1 to x do
      if a[i,j]>0
      then c:=c+1
  until c=x*y-w;
  writeln (t-1);
  close (input);
  close (output)
end.