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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
//package tester;

import java.util.Collections;
import java.util.Scanner;
import java.util.ArrayList;

/**
 * Codeforces round 526, problem A: King of Thieves
 * 
 * @author annyni
 *
 */
public class cf526pA {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String level = sc.next();
		sc.close();
		
		char[] lvlArr = level.toCharArray(); 
		
		for (int j=0; j<n; j++) {
			if (lvlArr[j]=='.') continue;
			boolean luls = false;
			for (int i=1; j+4*i<n; i++) {
				if (lvlArr[j+i]=='*') {
					if (lvlArr[j+2*i]=='*') {
						if (lvlArr[j+3*i]=='*') {
							if (lvlArr[j+4*i]=='*') {
								luls = true;
							}
						}
					}
				} if (luls) break;
			}
			if (luls) {
				System.out.println("yes");
				return;
			}
		}
		
		System.out.println("no");
	}

}
