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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.Scanner;

public class a {
	public static void main(String[] Args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String s = sc.next();
		boolean res = false;
		for(int k = 0; k < n; k++){
			for (int j = k+1; s.charAt(k)=='*' && j < n; j++){
				if (s.charAt(j)=='*'){
					int c = 1;
					int dx = j-k;
					int tj = j;
					while(c < 5 && tj < n && s.charAt(tj) =='*'){
						tj+= dx;
						c++;
					}
					if (c==5){
						res = true;
					}
				}
			}
		}
		System.out.println(res?"yes":"no");
	}
	public static long get(long n){
		int count = 2;
		int c = 1;
		while (n >= count) {
			n -= count;
			count *= 2;
			c++;
		}
		String ret = "";
		while (c != 0) {
			c--;
			if ((n & 1) != 0) {
				ret = "7" + ret;
			} else {
				ret = "4" + ret;
			}
			n /= 2;
		}
		return Long.parseLong(ret);
	}
}
