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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.util.Scanner;
/**
 * Created by loremon long time ago.
 */

public class Main {
    public static void main(String[] args) {
        Scanner read = new Scanner(System.in);

        boolean [] a;
        String s;
        boolean f;
        int i, j, k, n;
        n = Integer.valueOf(read.next());
        s = read.next();
        a = new boolean[n];
        for (i=0; i<n; i++) {
            if (s.charAt(i) == '*') a[i]=true;
            else a[i]=false;
        }
        for (i=0; i<n; i++) {
            if (!a[i]) continue;
            for (j=1; j<n; j++) {
                f=true;
                for (k=1; k<5; k++) {
                    if (i+k*j>=n) {
                        f=false;
                        break;
                    }
                    if (!a[i+k*j]) {
                        f=false;
                        break;
                    }

                }
                if (f) {
                    System.out.println("yes");
                    return;
                }
            }
        }
        System.out.println("no");


    }
}
