(*
ocamlfind ocamlopt -package batteries -linkpkg main.ml -o a.out
*)
open Batteries

let i, j = ref 0, ref 0
let f b = 
        if b then
                (* side effect *)
                (
                        incr i;
                        Printf.printf "Yes\n"
                )
        else
                Printf.printf "No\n"

let () =
        Scanf.sscanf (read_line ()) "%d %d %d" (
                fun _ a b -> 
                        Str.split (Str.regexp "") (read_line ())
                        |> List.iter
                                (function 
                                          "a" ->
                                                f (!i < a + b)
                                        | "b" -> 
                                                (* side effect *)
                                                (
                                                        incr j;
                                                        f (!i < a + b && !j <= b)
                                                ) 
                                        | _ -> 
                                                f false 
                                )
        )
