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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 competetive {

    public static void main(String[] args) throws java.lang.Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(java.io.FileDescriptor.out), "ASCII"), 512);
        int n=Integer.parseInt(br.readLine());
        String s=br.readLine();
        boolean flag=false;
        boolean w=false;
        for(int i=0;i<s.length();i++){
            if(s.charAt(i)=='*'){
                for(int j=1;i+j<n;j++){

                    int k=i+j;
                    boolean sub=false;
                    boolean s2=true;
                    int count=0;
                    while(k<n){
                        if(s.charAt(k)=='*'){
                            count++;
                            if(count==4&&s2){
                                sub=true;
                                break;
                            }
                        }else{
                            s2=false;
                        }
                        k+=j;
                    }
                    flag=sub;
                    if(flag&&!w){
                        out.write("yes");
                        w=true;
                        break;
                    }

                }
            }
        }
        if (!w){
            out.write("no"+'\n');
        }
        out.flush();
    }


}
