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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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;


public class Codeforces531A {
	public static void main(String[] args) {
		try
		{
			BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
			int n = Integer.parseInt(f.readLine());
			String s = f.readLine();
			char[] level = s.toCharArray();
			if(n < 5)
				System.out.println("no");
			else
			{
				boolean canMakeJump = false;
				for(int i = 0; i < n; i++)
				{
					//if(level[i] == '.')
					//	continue;
					for(int j = 1; j < n; j++)
					{
						int position = i;
						int count = 0;
						while(position < n && level[position] == '*' && count < 5)
						{
							position += j;
							count++;
						}
						if(count == 5)
						{
							canMakeJump = true;
							break;
						}
					}
					if(canMakeJump)
						break;
				}
				if(canMakeJump)
					System.out.println("yes");
				else
					System.out.println("no");
			}
		}
		catch(IOException e)
		{
			System.out.println(e);
		}

	}

}
