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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;

public class KingOfThieves {

	public static void main(String[] args) throws IOException {
		// BufferedReader reader = new BufferedReader(new
		// FileReader("/home/bala/temp/1/A-sample.in"));
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		reader.readLine();
		char[] in = reader.readLine().toCharArray();
		int firstPlatformLoc = 0;
		while (firstPlatformLoc < in.length && in[firstPlatformLoc] == '.')
			firstPlatformLoc++;
		boolean isPossible = false;
		for (int jumpLength = 1; jumpLength < in.length && !isPossible; jumpLength++) {
			int successiveCount = 0;
			for (int startLoc = firstPlatformLoc; startLoc < in.length; startLoc++) {
				for (int curLoc = startLoc; curLoc < in.length; curLoc += jumpLength) {
					if (in[curLoc] == '*')
						successiveCount++;
					else {
						successiveCount = 0;
						break;
					}
					if (successiveCount == 5) {
						isPossible = true;
						break;
					}
				}
			}
		}
		if (isPossible)
			System.out.println("yes");
		else
			System.out.println("no");
		// reader.close();
	}
}
