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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.*;
import java.io.*;

public class KingofThieves
{
	public static int n;
	public static String m;

	public static void main(String[] args)
	{
		Scanner sc = new Scanner(System.in);
		n = sc.nextInt();
		m = sc.next();
		boolean c = test();
		if (c) System.out.println("yes");
		else System.out.println("no");
	}
	
	public static boolean test()
	{
		//iterate upward the starting index
		int start = -1;
		while (true)
		{
			start++;
			if (start >= m.length()) return false;
			
			//if start isn't on a platform, don't bother
			if (m.charAt(start) == '*')
			{
				//iterate upward the jumping interval
				int jump = 1;
				while (jump < m.length())
				{
					
					//perform the check - for loop - iterate, then check 4 times
					int index = start;
					boolean c = true;
					for (int i = 0; i < 4; i++)
					{
						index += jump;
						if (index >= m.length() || m.charAt(index) == '.')
						{
							c = false;
							break;
						}
					}
					if (c) return true;
					
					//if nothing was found, iterate jump up
					jump++;
				}
			}
		}
	}
}