program ime;
 var x,r:char;
 var n,m,sumn,summ:real;
 var i:integer;

begin
 readln(n,r,m);
 i:=0;

 repeat
  readln(x);

  if x='B' then begin
   sumn:=sumn+0.3;
   summ:=summ+0.6;
   i:=i+1;
  end;

  if x='G' then begin
   sumn:=sumn+0.6;
   summ:=summ+0.3;
   i:=i+1;
  end;

 until (summ=m) or (sumn=n);

 writeln(i);
 readln;
 readln;

end.