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

public class CF_1237_1 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        sc.nextLine();
        String s=sc.nextLine();
        int a[]=new int[1000];
        for(int i=0;i<n;i++)
            if(s.charAt(i)=='*')
                a[i]=1;
        
        for(int i=1;i<=n/4;i++)
            for(int j=0;j<n;j++)
                if(a[j]==1){
                    int flag=1;
                    for(int k=1;k<=4;k++){
                        if(a[j+i]==1)
                            continue;
                        else
                            flag=0;                         
                    }
                    if (flag==1){
                        System.out.println("yes");
                        return;
                    }
                }       
        System.out.println("no");
        return;
    }

}
