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***************************************************************************************************
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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;

/**
 * Created by Андрей on 04.04.2015.
 */
public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.valueOf(in.readLine());
        String path = in.readLine();

        for (int i = 0; i < N - 4; ++i) {
            if (path.charAt(i) == '.') continue;
            for (int j = 1; j <= (N - 5 - i) / 4 + 1; ++j) {
                boolean flag = true;
                for (int k = 1; k < 5; ++k) {
                    //System.out.print(path.charAt(i + j));
                    if (path.charAt(i + j * k) != '*') {
                        flag = false;
                        break;
                    }
                }
                //System.out.println();
                if (flag) {
                    System.out.println("yes");
                    return;
                }
            }
        }
        System.out.println("no");
    }
}
