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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.*;
import java.util.*;
public class Main {
    public static void main(String args[]) {
        Cf526 hehe=new Cf526();
        hehe.solve();
    }
}

class Cf526 {
    void solve() {
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();
        String str=in.next();
        boolean vis[]=new boolean[str.length()];
        Arrays.fill(vis, false);
        for(int i=0;i<str.length();i++) {
            if(str.charAt(i)=='*') {
                vis[i]=true;
            }
        }
        boolean flag=false;
        for(int i=0;i<str.length();i++) {
            for(int j=1;j*4+i<str.length();j++) {
                if(str.charAt(i)=='*'&&str.charAt(i+j)=='*'&&str.charAt(i+j*2)=='*'&&str.charAt(j*3+i)=='*'&&str.charAt(i+4*j)=='*') {
                    flag=true;
                }
            }
        }
        if(flag) System.out.println("yes");
        else System.out.println("no");
    }
}
