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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 KingofThieves {

    public static void solve(String s, int n) {
        boolean good = false;
        for(int i = 0; i < n-4; i++) {
            int maxJump = (n - 1 - i) / 4;
            for(int j = 1; j <= maxJump; j++) {
                if(s.charAt(i) == '*' && s.charAt(i+j) == '*'
                    && s.charAt(i+2*j) == '*' && s.charAt(i+3*j) == '*'
                    && s.charAt(i+4*j) == '*') {
                    good = true;
                }
            }
        }
        if(good == true)
            System.out.println("yes");
        else
            System.out.println("no");
    }

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        String s = scan.next();
        solve(s, n);
    }
}