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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
//package zeptoLabCodeRush_20150403;

import java.util.Scanner;

public class Pb1 {
	static Scanner in = new Scanner(System.in);

	public static void main(String[] args) {
		int n = in.nextInt();
		String str = in.next();
		char [] s = str.toCharArray();
		for(int i=1;i<=n/4;i++){// i = step length
			for(int j=0;j+4*i<n;j++){// j = starting point
				if(s[j]=='*'&&s[j+i]=='*'&&s[j+2*i]=='*'&&s[j+3*i]=='*'&&s[j+4*i]=='*'){
					System.out.println("yes");
					return;
					}
			}//for j
		}//for i
		System.out.println("no");
		return;
	}// main()

}// class
