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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.Collection;
import java.util.Collections;
import java.util.Scanner;



public class Main {
	


	public static void main(String[] args) {
		Scanner in =new Scanner(System.in);
		int n=in.nextInt();
		char[] scheme=in.next().toCharArray();
		boolean isGood=false;
		check:
		for(int start=0;start<scheme.length;start++){
			for(int step=1; start+step*4<n ; step++){
				if(start+step*5<n) continue;
				isGood=true;
				for(int i=start;i<n;i+=step){
					if(scheme[i]!='*'){
						isGood=false;
						break;
					}
				}
				if(isGood)
					break check;
				
			}
		}
		System.out.print(isGood? "yes":"no");
		
		
	}

}
