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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
/* 
* @Author: steve
* @Date:   2015-05-26 23:31:26
* @Last Modified by:   steve
* @Last Modified time: 2015-05-26 23:39:14
*/
import java.io.*;

public class KingofThieves {
    public static void main(String[] args) throws Exception{
    	BufferedReader entrada = new BufferedReader(new InputStreamReader(System.in));
    	int n = Integer.parseInt(entrada.readLine());
    	String cad = entrada.readLine();
    	boolean esta=false;
    	for(int i=1;i<=n/5;i++){
    		for(int k=0;k<=i;k++){
    			int cont=0;
    			for(int j=k;j<n;j+=i)
    				if(cad.charAt(j)=='*')
    					cont++;
    			if(cont>=5) esta=true;
    		}
    	}
    	System.out.println((esta)?"YES":"NO");
    }
}