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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.ArrayList;
import java.util.Scanner;

public class KingThieves_526A {
public static void main(String args[])/*throws IOException*/{
	/*BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	int len=Integer.parseInt(br.readLine());
	String in=br.readLine();*/
	Scanner sc=new Scanner(System.in);
	int len=sc.nextInt();
	//String in=sc.nextLine();
	String in=sc.next();
	ArrayList<Integer> inPlat=new ArrayList<Integer>();
	boolean flag=false;

	for(int i=0;i<in.length();i++){
		if(in.charAt(i)=='*')
			inPlat.add(i);
	}
	
	for(int i=1;i<inPlat.size()-3;i++){
		int diff=inPlat.get(i)-inPlat.get(0);
		int currPlat=inPlat.get(i);
		int count=0;
		for(int j=i+1;j<inPlat.size();j++){
			if(diff+currPlat==inPlat.get(j)){
				count++;
				currPlat=inPlat.get(j);
			}
			if(count>=3){
				break;
			}
		}
		if(count>=3){
			flag=true;
			break;
		}
	}
	
	if(flag==true)
		System.out.println("yes");
	else
		System.out.println("no");

}
}
