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


public class Main {

	public static class pair implements Comparable<pair>
	{
		int a;
		int b;
		public pair(int pa, int pb)
		{
			a = pa; b= pb;
		}
		@Override
		public int compareTo(pair o) {
			if(this.a < o.a)
				return -1;
			if(this.a > o.a)
				return 1;
			return Integer.compare(o.b, this.b);
		}
	}


	//int n = Integer.parseInt(in.readLine());
	//int n = Integer.parseInt(spl[0]);
	//String[] spl = in.readLine().split(" ");
	
	public static void main (String[] args) throws Exception
	{	
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(in.readLine());
		boolean[] plat = new boolean[n];
		String s = in.readLine();
		for (int i = 0; i < n; i++) {
			if(s.charAt(i)=='*')
				plat[i]=true;
		}
		boolean found = false;
		for (int i = 0; i < n && !found; i++) {
			a: for (int j = i+1; j < n && !found; j++) {
				if(!plat[i] || !plat[j])
					continue;
				int diff = j-i;
				int cur = j;
				for (int k = 0; k < 3; k++) {
					if(cur + diff >= n || !plat[cur+diff])
						continue a;
					cur = cur + diff;
				}
				found = true;
			}
		}
		if(found)
			System.out.println("yes");
		else System.out.println("no");
	}

}