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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.Scanner;

/*

12
***.********

 */

public class a {

	public static void main(String[] args) 
	{
		Scanner in = new Scanner(System.in);
		
		int n = in.nextInt();
		String line = in.next();
		
		int count = 0;
		
		for(int start = 0; start < n && count < 4; ++start)
		{
			for(int len = 1; len+start <= n && count < 4; ++len)
			{
				int c = 0;
				for(int jump = 0; jump < (n-start) / len && jump < 5 && line.charAt(start + len*jump) == '*'; ++jump)
				{
					//System.out.println("Start: "+start +", len: "+len +", jump: "+jump);
					++c;
				}
				count = Math.max(c, count);
			}
		}
		
		if(count >= 4)
			System.out.println("yes");
		else
			System.out.println("no");
		
		in.close();
	}

}
