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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.io.*;
import java.util.*;

public class zepta {
	public static void main(String[] args) throws Exception {
		//Scanner in = new Scanner(new File("zepta.in"));
		//PrintStream out = new PrintStream(new File("zepta.out"));
		Scanner in = new Scanner(System.in);
			in.nextLine();
			String temp = in.nextLine();
			char[] w = new char[temp.length()];
			for(int i=0;i<temp.length();i++)
				w[i]=temp.charAt(i);
			boolean possible = false;
			for(int j = 0;j<w.length;j++){
				for(int k = 1;k<w.length;k++){
					boolean ihatecs=true;
					for(int a=0;a<5;a++)
					{
						if(!(j+k*a<w.length&&w[j+k*a]=='*')){
							ihatecs = false;
						}

					}
					if(ihatecs)
						possible = true;
				}
			}	
			if(possible)
				System.out.println("yes");
			else
				System.out.println("no");
			
		
	}
}