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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.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Scanner;

public class Solution1 {
    public static void main(String args[]){
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String s = in.next();
        
        boolean poss = false;
        for(int j=0;j<n;j++){
            if(poss){
                break;
            }
            for(int i=1;i<=((n-j)/4);i++){
                if(possible(s,j,i)){
                    //System.out.println(j+" "+i);
                    poss = true;
                    break;
                }
            }
        }
        if(s.length()<n){
            poss = false;
        }
        if(poss){
            System.out.println("yes");
        }else{
            System.out.println("no");
        }
    }
    public static boolean possible(String s, int startIndex,int diff){
        int score = 0;
        //System.out.println(startIndex+" "+diff);
        for(int i=startIndex;i<s.length()&& i<startIndex+(5*diff);i+=diff){
            if(s.charAt(i)=='*'){
                score++;
            }else{
                return false;
            }
            if(score==5){
                break;
            }
        }
        //System.out.println(score);
        if(score==5)
        return true;
        else
        return false;
    }
}