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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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import static java.lang.Integer.parseInt;

/**
 * TODO: describe
 *
 * @author keks
 */
public class AA {
    public static void main(String[] args) throws IOException {
        final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        final int n = parseInt(reader.readLine());
        final String s = reader.readLine();
        final char[] a = s.toCharArray();

        for (int k = 1; k < n / 4 + 1; k++) {
            for (int i = 0; i <= k; i++) {
                int count = 0;
                for (int j = i + k; j < n; j += k) {
                    if (a[j] == '*') count++;
                    else count = 0;
                    if (count == 4) {
                        System.out.println("yes");
                        return;
                    }
                }
            }
        }

        System.out.println("no");
    }
}
