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

public class ZeptoLabs_A {
	public static void main(String[] args) throws IOException {
		BufferedInputStream bis = new BufferedInputStream(System.in);
		BufferedReader br = new BufferedReader(new InputStreamReader(bis));
		int n = Integer.parseInt(br.readLine().trim());
		char [] dungeon = br.readLine().toCharArray();
		System.out.println(getAns(dungeon));
	}
	public static String getAns(char [] d) {
		int n = d.length;
		for(int i = 1;i <= n-1;i++) {
			for(int start = 0;start < n-i;start++) {
				boolean ans = true;
				for(int j = 0;j < 5 && ans;j++) {
					if(start+i*j < n && d[start+i*j] != '*')
						ans = false;
					if(start+i*j >= n)
						ans = false;
				}
				if(ans)
					return "yes";
			}
		}
		return "no";
	}
}