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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 a1 {
	public static void main(String[] args) throws FileNotFoundException {
		Scanner in = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		int n = in.nextInt();
		String s = in.next();
		boolean fl = false;
		for (int i = 0; i < n; i++) {
			for (int j = 1; j < n; j++) {
				if (i + 4 * j <= n - 1){
					boolean flag = true;
					for (int j2 = i; j2 < i + 5 * j; j2 += j) {
						if (s.charAt(j2) != '*'){
							flag = false;
							break;
						}
					}
					if (flag){
						fl = true;
						break;
					}
				}
			}
		}
		if (fl){
			out.println("yes");
		}
		else{
			out.println("no");
		}
		out.close();
	}
}
