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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.util.Scanner;


public class A {

	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		
		int n=Integer.parseInt(sc.nextLine());
		char line[]=sc.nextLine().toCharArray();
		
		int max=(int)(Math.ceil((double)n/5));		
		boolean found=false;		
		int paso=1;
		int count=0;
		int j=0;
		
		for(paso=1;paso<=max && found==false;paso++){
			for(int i=0;i<paso && found==false;i++){
				j=i;
				while(j<n && count<=5){
					if(line[j]=='*'){
						count++;
					}else{
						count=0;
					}
					j=j+paso;
				}
				if(count>=5){
					System.out.println("yes");
					found=true;
				}
			}			
		}
		
		if(!found){
			System.out.println("no");
		}
	}
}
