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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.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 *
 * @author таня
 */
public class JavaApplication20 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
    N1138 jk = new N1138();
    }
}
class N1138 {

Scanner in = new Scanner(System.in);
PrintWriter out = new PrintWriter(System.out);
int n = in.nextInt();
String s = in.next();

    public N1138() throws IOException {
    //    in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
      //  out = new PrintWriter(new OutputStreamWriter(System.out));
        char str[]=s.toCharArray();
        int max_cnt=0;
        for(int i=1;i<n;i++){
            int cnt=0;
            for(int k=0;k<n;k++){
            for(int j=k;j<n;j+=i){
            if(str[j]=='.'){
            cnt=0;
            }else{
            cnt++;
            }
            }
            if(cnt>max_cnt){
            max_cnt=cnt;
            }
        }
        }
        if(max_cnt>=5){
        out.print("yes");
        }else{
         out.print("no");
        }
        out.flush();
}
}