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***************************************************************************************************
 5
****.

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;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Random;
import java.util.StringTokenizer;

public class ZCRA {

  static BufferedReader in;
  static PrintWriter out;
  static StringTokenizer tok;

  static void solve() throws Exception {
    int n = nextInt();
    char[] c = next().toCharArray();
    for (int d = 1; d <= (n - 1) / 4; d++)
      for (int i = 0; i + 4 * d < n; i++) {
        if (c[i] == '*' && c[i + d] == '*' && c[i + 2 * d] == '*' && c[i + 3 * d] == '*'
            && c[i + 4 * d] == '*') {
          out.println("yes");
          return;
        }
      }
    out.println("no");
  }

  public static void main(String args[]) {
    try {
      in = new BufferedReader(new InputStreamReader(System.in));
      out = new PrintWriter(new OutputStreamWriter(System.out));
      solve();
      in.close();
      out.close();
    } catch (Throwable e) {
      e.printStackTrace();
      System.exit(1);
    }
  }

  static int nextInt() throws IOException {
    return Integer.parseInt(next());
  }

  static int[] nextIntArray(int len, int start) throws IOException {
    int[] a = new int[len];
    for (int i = start; i < len; i++)
      a[i] = nextInt();
    return a;
  }

  static long nextLong() throws IOException {
    return Long.parseLong(next());
  }

  static long[] nextLongArray(int len, int start) throws IOException {
    long[] a = new long[len];
    for (int i = start; i < len; i++)
      a[i] = nextLong();
    return a;
  }

  static double nextDouble() throws IOException {
    return Double.parseDouble(next());
  }

  static double[] nextDoubleArray(int len, int start) throws IOException {
    double[] a = new double[len];
    for (int i = start; i < len; i++)
      a[i] = nextDouble();
    return a;
  }

  static BigInteger nextBigInteger() throws IOException {
    return new BigInteger(next());
  }

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

  static String nextLine() throws IOException {
    tok = new StringTokenizer("");
    return in.readLine();
  }

  static void shuffleArray(long[] array) {
    Random random = new Random();
    for (int i = array.length - 1; i > 0; i--) {
      int index = random.nextInt(i + 1);
      long temp = array[index];
      array[index] = array[i];
      array[i] = temp;
    }
  }

  static boolean hasNext() throws IOException {
    while (tok == null || !tok.hasMoreTokens()) {
      String s = in.readLine();
      if (s == null) {
        return false;
      }
      tok = new StringTokenizer(s);
    }
    return true;
  }

}
