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

public class zeptothief{
	public static void main(String args[]) throws Exception{
		Scanner input=new Scanner(System.in);
		int N=input.nextInt();
		String level=input.next();
//		System.out.println(level);
		for(int i=0; i<N; i++){
			loop:
			for(int j=1; j<N; j++){
//				System.out.println(i+" "+j);
				for(int k=0; k<5; k++){
//					System.out.print(level.charAt(i+j*k));
					if((i+j*k)>=level.length()){
						continue loop;
					}
					if(level.charAt(i+j*k)!='*'){
						continue loop;
					}
				}
				System.out.println("yes");
				return;
			}
		}
		System.out.println("no");
	}
}