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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 java.util.StringTokenizer;

public class KingOfThieves {
	public static BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
	public static StringTokenizer st;
	
	public static void main(String[] args) throws IOException {
		int n = nextInt();
		String s = nextString();
		
		for (int i = 0; i < n; i++)
			for (int j = 1; i+4*j < n; j++) {
				boolean b = true;
				for (int k = 0; k < 5; k++)
					b &= s.charAt(i+k*j) == '*';
				if (b) {
					System.out.println("yes");
					return;
				}
			}
		
		System.out.println("no");
	}
	
	public static String nextLine() throws IOException {
		return f.readLine();
	}
	
	public static String nextString() throws IOException {
		while (st == null || !st.hasMoreTokens())
			st = new StringTokenizer(f.readLine());
		return st.nextToken();
	}
	
	public static int nextInt() throws IOException {
		return Integer.parseInt(nextString());
	}
	
	public static long nextLong() throws IOException {
		return Long.parseLong(nextString());
	}
	
	public static int[] intArray(int n) throws IOException {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	}
	
	public static int[][] intArray(int n, int m) throws IOException {
		int[][] a = new int[n][m];
		for (int i = 0; i < n; i++)
			for (int j = 0; j < m; j++)
				a[i][j] = nextInt();
		return a;
	}
	
	public static long[] longArray(int n) throws IOException {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nextLong();
		return a;
	}
}