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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.util.*;

public class Problema_java1{
	public static void main (String[] args){
		Scanner entrada = new Scanner (System.in);

		int x;
		int[] dif = new int[5];
		int teste = 0;
		int sum = 0;
		x = entrada.nextInt();

		char[] plataforma = new char[x];
		int [] vector = new int[x];
		String string = entrada.next();
		int aux = 0;
		plataforma = string.toCharArray();

		for(int i = 0; i < x; i++){
			vector[i] = 0;
			if(plataforma[i] == '*'){
				vector[i] = 1; 
			}
		}

		for(int i = 0; i < x ;i++){
			sum  = 0;
			if(vector[i] == 1){
				for(int j = (i + 1); j < x; j++){
					if(vector[j] == 1){
						aux = j - i;
						break;
					}
				}
				for(int j = i; j < x; j+=aux){
					if(vector[j] == 1){
						sum++;
					}
					else 
						break;
				}
			}
			if(sum > 4){
				System.out.println("yes");
				break;
			}
			sum  = 0;
		}
		if(sum < 4){
			System.out.println("no");
		}
	}
}