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 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.util.*;
import java.io.*;

public class Solution{
	
	BufferedReader br;

	public void run() throws IOException{
		br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine().trim());
		String str = br.readLine().trim();

		char [] arr = str.toCharArray();
		int len = arr.length;
		int count = 0;

		for(int j=1;j<=(len-1)/4;j++){
			for(int i=0;i<len;i++){
				int start = i;

				if(arr[start] == '.')	
					continue;
				
				while(start+j<len){
					if(arr[start+j] == '.')
						break;
					count++;
					start += j;
					if(count >=4)
						break;
				}

				if(count>=4)
					break;
				else
					count = 0;
			}
			if(count>=4)
				break;
			else
				count = 0;
		}

		if(count >=4)
			System.out.println("yes");
		else
			System.out.println("no");
	}

	public static void main(String [] args)throws IOException{
		new Solution().run();
	}
}

