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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.*;

public class Main {

    public static void main(String[] args) throws IOException {
        new Main().run();
    }

    private void run() throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.valueOf(bf.readLine());
        String s = bf.readLine();
        int i = 0;
//        while(s.charAt(i)!='*'){
//            i++;
//        }
        boolean flag = false;
        int k = 1;
        while(i+k*4<n){
            if(s.charAt(i)!='*'){
                i++;
                continue;
            }
            flag = false;
            if (s.charAt(i+k)=='*' && s.charAt(i+k+k)=='*' && s.charAt(i+k+k+k)=='*' && s.charAt(i+k+k+k+k)=='*' ){
                flag = true;
                break;
            }

            k++;
            if(i+k*4==n){
                k=1;
                i++;
            }
        }
        if(flag){
            System.out.println("yes");
        } else
        {
            System.out.println("no");
        }
    }
}
