20
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 5
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 6
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 53
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 10
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 98
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 13
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 99
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 99
***************************************************************************************************
 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.util.*;

public class cfzA {
	public static void main(String[] args) throws Exception {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		// BufferedReader in = new BufferedReader(new FileReader("cfzA.in"));

		int n = Integer.parseInt(in.readLine());
		boolean works = false;
		String str = in.readLine();
		for(int i = 0; i < 100; i++) {
			for(int j = 1; j < 100; j++) {
				boolean works2 = true;
				for(int k = 0; k < 5; k++) {
					if(!(i + j * k < n && str.charAt(i + j * k) == '*')) {
						works2 = false;
					}
				}
				if(works2) {
					works = true;
				}
			}
		}
		System.out.println(works ? "yes" : "no");
	}
}