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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
import java.io.*;
import java.util.*;

public class housie{   
     public static void main(String[]args) throws IOException {             
                 BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
                 PrintWriter pw=new PrintWriter(new OutputStreamWriter(System.out));
                 BufferedWriter bw=new BufferedWriter(pw);
                 int n=Integer.parseInt(br.readLine());
                 String s2=br.readLine();
                 int temp=0,d=0;
                 for(int i=0;i<n;i++){
                     if(s2.charAt(i)=='*'){
                         for( d=1;d<n;d++){
                             int count=0;
                             for(int j=i+d;j<n;j+=d){
                                 if(s2.charAt(j)!='*'){
                                    count=0;
                                     break;
                                 }
                                 else{
                                     count++;
                                 }
                                 if(count==4){
                                   //  System.out.println(j);
                                     temp=1;
                                     break;
                                 }
                             }
                             if(temp==1){
                                 break;
                             }
                         }
                     }
                     if(temp==1){
                       //System.out.println(d);
                         break;
                     }
                 }
                 
                 if(temp>0){
                     pw.print("yes");
                 }
                 else{
                     pw.print("no");
                 }
                 
                     
                pw.flush();
      }
}
                
                