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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.*;
import java.util.*;

public class A {

    public void solve() throws IOException {
        int n = in.nextInt();
        char[] s = in.nextToken().toCharArray();
        for (int i = 0; i < n; i++) {
            for (int d = 1; i + 4 * d < n; d++) {
                boolean ok = true;
                for (int j = 0; j < 5; ++j) {
                    ok &= s[i + j * d] != '.';
                }
                if (ok) {
                    out.println("yes");
                    return;
                }
            }
        }
        out.println("no");
    }

    static FastReader in;
    static PrintWriter out;
    static PrintStream err;

    public static void main(String[] args) throws IOException {
        try {
            in = new FastReader();
            out = new PrintWriter(System.out);
            err = System.err;
            new A().solve();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }
}

class FastReader {
    BufferedReader br;
    StringTokenizer in;

    FastReader() {
        this.br = new BufferedReader(new InputStreamReader(System.in));
    }

    FastReader(String filename) {
        try {
            this.br = new BufferedReader(new FileReader(filename));
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    public String nextToken() throws IOException {
        while (in == null || !in.hasMoreTokens()) {
            in = new StringTokenizer(br.readLine());
        }
        return in.nextToken();
    }

    public int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    public double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }

    public long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }
}