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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
/*
ID: wilbs43
LANG: JAVA7
STATUS: incomplete
 */
import java.io.*;
import java.util.*;

public class CF526A {
	public static void main(String[] args) throws IOException {
		BufferedReader in;
		//in = new BufferedReader(new FileReader(new File("CF526A.in")));
			in = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(in.readLine().trim());
		char[] line = in.readLine().toCharArray();
		
		
		
		
		System.out.println(check(n,line));
		in.close();
	}

	public static boolean check(int n, char[] field) {
		for (int i = 0; i < n-5; i++) {
			for (int sep = 1; i+4*sep < n; sep++) {
				int jump = 0;
				for (; jump < 5; jump++) {
					if(field[i+jump*sep]!='*') {
						break;
					}
				}
				if(jump==5) return true;
			}
		}		
		return false;
	}
}