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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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


public class Main{

	static int N;
	static boolean isGood(char[]c){
		for(int i=0;i<N;i++){
			if(c[i]=='*'){
				for(int d=1;i+4*d<N;d++){
					if(c[i+d]=='*'&&c[i+2*d]=='*'&&c[i+3*d]=='*'&&c[i+4*d]=='*')
						return true;
				}
			}
		}
		return false;
	}
	public static void main(String[] args)throws IOException,NumberFormatException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		N=Integer.parseInt(br.readLine());
		char[] c=br.readLine().toCharArray();
		if(isGood(c))
			System.out.println("yes");
		else
			System.out.println("no");
		

	}

}
