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****.

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import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Q256A {

  /**
   * @param args
   */
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int number = sc.nextInt();
    String path = sc.next();
    List stars = getPositions(path, "*");
//    System.out.println(stars);
    boolean result = isGood(stars);
    System.out.println(result?"yes":"no");

  }
  public static boolean isGood(List<Integer> stars){
    if(stars.size()<5)
      return false;
    for(int i=0;i<stars.size()-4;i++){
      for(int j=i+1;4*(j-i)+i<stars.size();j++){
        int dt = stars.get(j)-stars.get(i);
        List<Integer> expectedPos = new ArrayList<Integer>();
        expectedPos.add(stars.get(i));
        expectedPos.add(stars.get(i)+dt);
        expectedPos.add(stars.get(i)+2*dt);
        expectedPos.add(stars.get(i)+3*dt);
        expectedPos.add(stars.get(i)+4*dt);
        if(stars.containsAll(expectedPos)){
          return true;
        }
      }
    }
    return false;
  }

  public static List<Integer> getPositions(String str, String sub){
    List<Integer> result =new ArrayList<Integer>();
    int start = 0;
    while (start <str.length()) {
        int index = str.indexOf(sub, start);
        if(index==-1){
          break;
        }
        result.add(index);
        start = index+1;
    }
    return result;
  }
}
