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***************************************************************************************************
 5
****.

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.*;
import java.math.BigInteger;
import java.util.*;


public class Program {
	void solve() throws IOException {
		int n = nextInt();
		String str = nextToken();
		boolean yn = false;
		int d = (n - 1) / 4;
		int count;
		for (int i = 0; i < d; i++) {
			for (int j = d; j > 0 ; j--) {
				count = 0;
				for (int k = 0; k < n;) {
					if(str.charAt(k) == '.') {
						if (k + 4*j + 1 < n) {
							count=0;
							k+=1;
						}
						else
							break;
					}
					else
					{
						count+=1;
						if (count == 5) {
							yn = true;
							break;
						}
						k += j;
					}
				}
				if (yn)
					break;
			}
			if (yn)
				break;
		}
		out.println(yn?"yes":"no");
	}

	public static void main(String[] args) throws IOException {
		new Program().run();
	}

	void run() throws IOException {
		reader = new BufferedReader(new InputStreamReader(System.in));
		tokenizer = null;
		out = new PrintWriter(new OutputStreamWriter(System.out));
		solve();
		reader.close();
		out.flush();
	}


	BufferedReader reader;
	StringTokenizer tokenizer;
	PrintWriter out;

	int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	long nextLong() throws IOException {
		return Long.parseLong(nextToken());
	}

	double nextDouble() throws IOException {
		return Double.parseDouble(nextToken());
	}

	String nextToken() throws IOException {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			tokenizer = new StringTokenizer(reader.readLine());
		}
		return tokenizer.nextToken();
	}
}