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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.awt.Point;
import java.io.*;
import java.lang.Integer;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.*;
import java.util.ArrayDeque;

import static java.lang.Math.*;

public class Main {

    final boolean ONLINE_JUDGE = !new File("input.txt").exists();
    BufferedReader in;
    PrintWriter out;
    StringTokenizer tok = new StringTokenizer("");

    void init() throws FileNotFoundException {
        if (ONLINE_JUDGE) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        } else {
            in = new BufferedReader(new FileReader("input.txt"));
            out = new PrintWriter("output.txt");
        }
    }

    String readString() throws IOException {
        while (!tok.hasMoreTokens()) {
            tok = new StringTokenizer(in.readLine());
        }
        return tok.nextToken();
    }

    int readInt() throws IOException {
        return Integer.parseInt(readString());
    }

    long readLong() throws IOException {
        return Long.parseLong(readString());
    }

    double readDouble() throws IOException {
        return Double.parseDouble(readString());
    }

    public static void main(String[] args) {
        new Main().run();
        // Sworn to fight and die
    }

    public void run() {
        try {
            long t1 = System.currentTimeMillis();
            init();
            solve();
            out.close();
            long t2 = System.currentTimeMillis();
            System.err.println("Time = " + (t2 - t1));
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.exit(-1);
        }
    }

    class LOL implements Comparable<LOL> {
        long count;
        long type;

        public LOL(long time, long num) {
            this.count = time;
            this.type = num;
        }

        @Override
        public int compareTo(LOL o) {

            if (o.count != count)
                return (int) (o.count - count); // ---->
            return (int) (o.type - type); // <----
        }

    }

    public long gcd(long a, long b) {
        if (a % b == 0)
            return b;
        else
            return gcd(b, a % b);
    }

    public int gcd(int a, int b) {
        if (a % b == 0)
            return b;
        else
            return gcd(b, a % b);
    }

    boolean prime(int n) {
        for (int i = 2; i <= sqrt(n); i++)
            if (n % i == 0)
                return false;
        return true;
    }



    public void solve() throws IOException {
       int n = readInt();
        char[] s = readString().toCharArray();
        for (int i = 0; i < n - 4; i++)
            for(int j = 1; j <= (n - i - 1)/4; j++)
                if(s[i] == '*' && s[i+j] == '*' && s[i+2*j] == '*'&& s[i+3*j] == '*'&& s[i+4*j] == '*') {
                    out.print("yes");
                    return;
                }
        out.print("no");
    }

}