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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.io.*;
import java.util.*;


public class Source {
    static class FastScanner {
        private BufferedReader br;
        private StringTokenizer st;
        public FastScanner(InputStream inputStream){
            br = new BufferedReader(new InputStreamReader(inputStream));
        }
        public String next() {
            while (st == null || !st.hasMoreTokens()){
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException ignored){}
            }
            return st.nextToken();
        }
        public int nextInt() {
            return Integer.parseInt(next());
        }
        public long nextLong() {
            return Long.parseLong(next());
        }
        public double nextDouble() {
            return Double.parseDouble(next());
        }
    }

    public static void main(String args[]){
        FastScanner scanner = new FastScanner(System.in);
        PrintWriter printer = new PrintWriter(System.out);
        int n = scanner.nextInt();
        String s = scanner.next();
        for(int k=1;k<n;k++){
            for(int i=0;;i++){
                if(i+k*4 >= n){
                    break;
                }
                boolean c1 = s.charAt(i) == '*';
                boolean c2 = s.charAt(i+k) == '*';
                boolean c3 = s.charAt(i+k*2) == '*';
                boolean c4 = s.charAt(i+ k*3) == '*';
                boolean c5 = s.charAt(i+k*4) == '*';
                if(c1 && c2 && c3 && c4 && c5){
                    printer.println("yes");
                    printer.close();
                    return;
                }
            }
        }
        printer.println("no");
        printer.close();
    }
}
