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


public class ZepoLabA {

	public static void main(String[] args) {
		FastScanner in=new FastScanner();
		int n=in.nextInt();
		String s=in.nextToken();
		
		for(int i=0;i<n;i++){
			for(int j=1;j<=n;j++){
				int cnt=0;
				for(int k=0;k<5;k++){
					if(i+k*j<n&&s.charAt(i+k*j)=='*')
						cnt++;
				}
				if(cnt==5){
					System.out.println("yes");
					return;
				}
					
			}
		}
		System.out.println("no");
	}
	static class FastScanner{
		BufferedReader br;
		StringTokenizer st;
		public FastScanner(){br=new BufferedReader(new InputStreamReader(System.in));}
		String nextToken(){
			while(st==null||!st.hasMoreElements())
				try{st=new StringTokenizer(br.readLine());}catch(Exception e){}
			return st.nextToken();
		}
		int nextInt(){return Integer.parseInt(nextToken());}
		long nextLong(){return Long.parseLong(nextToken());}
		double nextDouble(){return Double.parseDouble(nextToken());}
	}
}
