object Main extends App {
  import scala.io.StdIn.readLine

    var winState = readLine.split(" ").tail.map(_.toInt)
    var players = readLine
  
  	def solve(a:Int,b:Int,arr:String):List[String]= {
      if(arr.isEmpty)return Nil
      else if(arr.head == 'a' && a>0){return "Yes"::(solve(a-1,b,arr.tail))}
      else if(arr.head == 'b' && a>0 && b>0){return "Yes"::(solve(a-1,b-1,arr.tail))}
      else return "No"::(solve(a,b,arr.tail))
    }
  
    solve(winState.sum,winState.last,players).map(println(_));
}
