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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.math.BigInteger;
import java.util.*;


public class Zep1 {

    void solve() throws IOException {
        int n=nextInt();
        char[] c=reader.readLine().toCharArray();
        boolean ch=false;
        for(int j=0;j<c.length;j++){
            if(c[j]=='*'){
                for(int i=1;i<c.length;i++){
                    if(j+4*i>=c.length){
                        break;
                    }else{
                        if(c[j]=='*'&&c[j+i]=='*'&&c[j+2*i]=='*'&&c[j+3*i]=='*'&&c[j+4*i]=='*'){
                            ch=true;
                            break;
                        }
                    }
                }
            }
        }
        if(ch){
            out.print("yes");
        }else{
            out.print("no");
        }
    }



    public static void main(String[] args) throws IOException {
        new Zep1().run();
    }

    void run() throws IOException {
    	reader = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(new OutputStreamWriter(System.out));
//        reader = new BufferedReader(new FileReader("input.txt"));
//        out = new PrintWriter(new FileWriter("output.txt"));
        tokenizer = null;
        solve();
        reader.close();
        out.flush();

    }

    BufferedReader reader;
    StringTokenizer tokenizer;
    PrintWriter out;

    int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }

    String nextToken() throws IOException {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }
}