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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.*;
import java.lang.*;
import java.lang.Math;

public class A{
	static int n; static String s;
	public static void main(String[] args)throws Exception{
		n=Integer.parseInt(reader.readNextLine());
		s=reader.readNextLine();
		int i,j,k;
		for (k=1;k<n;k++) for (i=0;i<n;i++){
			for (j=0;j<5;j++){
				if ((i+(k*j))>=n) break;
				if (s.charAt(i+(k*j))=='.') break;
			}
			if (j>=5) {
				System.out.println("yes");
				System.exit(0);
			}
		}
		System.out.println("no");
	}
	
	static class reader{
		static BufferedReader bReader=new BufferedReader(new InputStreamReader(System.in));
		static StringTokenizer token=new StringTokenizer("");
		static String readNextLine() throws Exception{
			return bReader.readLine();
		}
		static String next() throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return token.nextToken();
		}
		static int nextInt()throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return Integer.parseInt(token.nextToken());
		}
		static long nextLong()throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return Long.parseLong(token.nextToken());
		}
		static double nextDouble()throws Exception{
			while (token.hasMoreTokens()==false){
				token=new StringTokenizer(bReader.readLine());
			}
			return Double.parseDouble(token.nextToken());
		}
	}
}
