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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;
		int jumpLength = 0, startLoc = 0, curLoc = 0;
		for (jumpLength = 1; jumpLength < in.length && !isPossible; jumpLength++) {
			for (startLoc = firstPlatformLoc; startLoc < in.length; startLoc++) {
				int successiveCount = 0;
				for (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");
//			System.out.println(jumpLength + "\t" + startLoc + "\t" + curLoc);
		} else
			System.out.println("no");
		// reader.close();
	}
}
