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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.IOException;
import java.io.InputStreamReader;

public class KingOfThieves {
    static String line;
    static int n;

    public static void main(String[] args) throws NumberFormatException, IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        n = Integer.parseInt(br.readLine());
        line = br.readLine();

        boolean done = false;
        for (int i = 0; i < n && !done; i++) {
            if (line.charAt(i) == '*'){
                for (int j = i+1; j < n && !done; j++) {
                    if (line.charAt(j) == '*'){
                        int diff = j-i;
                        if (isGood(j+diff,diff)){
                            done = true;
                            break;
                        }
                    }
                }
            }
        }

        if (done)
            System.out.println("yes");
        else
            System.out.println("no");

    }

    public static boolean isGood(int start,int diff){
        int count = 1;
        for (int i = start; i < n; i+=diff) {
            if (line.charAt(i) != '*')
                return false;
            count++;
            if (count == 4)
                return true;
        }
        return false;
    }

}
