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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.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{

	// split de array
	public static int[] readInts(String cad) {
		String read[] = cad.split(" ");
		int res[] = new int[read.length];
		for (int i = 0; i < read.length; i++) {
			res[i] = Integer.parseInt(read[i]);
		}
		return res;
	}

	public static void main(String[] args) throws IOException {
		long inicio = System.currentTimeMillis();
		StringBuilder out = new StringBuilder();
		BufferedReader in;
		File archivo = new File("entrada");
		if (archivo.exists())
			in = new BufferedReader(new FileReader(archivo));
		else
			in = new BufferedReader(new InputStreamReader(System.in));

		int n = Integer.parseInt(in.readLine());
		char map[] = in.readLine().toCharArray();
		int ini = 0;
		for (int i = 0; i < map.length; i++) {
			if (map[i] == '*') {
				ini = i;
				break;
			}
		}
		boolean c = false;
		for (int k = 0; k < map.length; k++) {
			if (map[k] == '*')
				for (int i = 1; i < map.length && !c; i++) {
					int temp = k;
					int cont = 0;
					boolean flag = false;
					while (temp + i < map.length && !flag) {
						if (map[temp + i] == '*') {
							temp = temp + i;
							cont++;
						} else {
							flag = true;
						}
					}

					if (cont >= 4 && flag == false) {
						c = true;
					}
				}
		}

		if (c) {
			System.out.println("yes");
		} else {
			System.out.println("no");
		}

		if (archivo.exists())
			System.out.println("Tiempo transcurrido : "
					+ (System.currentTimeMillis() - inicio) + " milisegundos.");
	}
}
