Program milkweed;

Type
sc=array [1..100,1..100] of longint;

Var
i,j:longint;
s,shizi:sc;
x,y:longint;
m,n,t:longint;
c:char;
o,o1,o2:boolean;

Begin
assign(input,'milkweed.in');
assign(output,'milkweed.out');
reset(input);
rewrite(output);
readln(n,m,x,y);
for i:=1 to m do
 for j:=1 to n do
  s[i,j]:=-2;
for i:=1 to m do begin
 for j:=1 to n do begin
  read(c);
  if c='*' then s[i,j]:=-1;
 end;
 readln;
end;
x:=m-x+1;
s[x,y]:=0;
o:=true;
t:=0;
while o=true do begin
 t:=t+1;
 o1:=false;
 for i:=1 to m do begin
  for j:=1 to n do begin
   if s[i,j]=t-1 then begin

    if j-1>=1 then begin
     if s[i,j-1]=-2 then begin
      s[i,j-1]:=t;
      o1:=true;
     end;
    end;
    if j+1<=n then begin
     if s[i,j+1]=-2 then begin
      s[i,j+1]:=t;
      o1:=true;
     end;
    end;

    if (i-1)>=1 then begin
     if s[i-1,j]=-2 then begin
      s[i-1,j]:=t;
      o1:=true;
     end;
     if j-1>=1 then begin
      if s[i-1,j-1]=-2 then begin
       s[i-1,j-1]:=t;
       o1:=true;
      end;
     end;
     if j+1<=n then begin
      if s[i-1,j+1]=-2 then begin
       s[i-1,j+1]:=t;
       o1:=true;
      end;
     end;
    end;

    if (i+1)<=n then begin
     if s[i+1,j]=-2 then begin
      s[i+1,j]:=t;
      o1:=true;
     end;
     if j-1>=1 then begin
      if s[i+1,j-1]=-2 then begin
       s[i+1,j-1]:=t;
       o1:=true;
      end;
     end;
     if j+1<=n then begin
      if s[i+1,j+1]=-2 then begin
       s[i+1,j+1]:=t;
       o1:=true;
      end;
     end;
    end;
   end;
  end;
 end;
 o2:=true;
 for i:=1 to m do
  for j:=1 to n do
   if s[i,j]=-2 then o2:=false;
 if o2=true then o:=false;
 if (o1=false)and(o=true) then begin
  writeln('-1');
  close(input);
  close(output);
  halt;
 end;
end;
writeln(t);
close(input);
close(output);
End.