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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
import java.io.*;
import java.util.Scanner;
public class Solution{
   public static void main(String[] args) throws FileNotFoundException{
       Scanner scanner = new Scanner(System.in);
       int n = scanner.nextInt();
       String map = scanner.next();
       char c[] = map.toCharArray();
       boolean b = false;
       for(int i=1;i<=n/4;i++){
            int s = 0;
            for(int k=0;k<i;k++){
	            for(int j=0;j<n/i;j++){
	                if(k+(i*j) < n  && c[k+i*j] == '*'){
	                    s ++;
	                    if(s >= 5){
	                        b = true;
	                        break;
	                        
	                    }
	                }else{
	                   s = 0;
	                }
	            }
            }
           if(b){
               break;
           }
       }
      if(b){
         System.out.println("yes");
       }else{
    	   System.out.println("no");
       }
   }
}