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 5
****.

no yes no no no yes yes no yes yes yes yes yes yes no yes yes yes yes yes yes yes yes yes yes yes no no no yes yes yes yes no no yes yes yes yes yes no yes yes no no no yes yes no yes yes no no no yes yes yes yes no yes yes yes no
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */



import java.util.Scanner;

/**
 *
 * @author Gustavo
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        Scanner sc=new Scanner(System.in);
        while(sc.hasNext()){
            int longitud=Integer.parseInt(sc.nextLine());
            String nivel=sc.nextLine();
            char[] segmentos=nivel.toCharArray();
            boolean valor=false;
            int pasos=segmentos.length/4;
            for(int i=1;i<pasos;i++){
                int pos=1;
                valor=false;
                while(!valor && pos<segmentos.length){
                    
                    if(segmentos[pos]=='.'){
                        valor=true;
                    }
                    pos+=i;
                }
                if(!valor){
                    
                    break;
                }
            }
            if(!valor){
                System.out.println("yes");
            }else{
                System.out.println("no");
            }
            
            
            
        }
        
    }
    
}
