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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.util.*;
import java.io.*;
public class juegomarica{
public static void main(String args[]) throws IOException{
BufferedReader lector = new BufferedReader(new InputStreamReader(System.in));
int a = Integer.parseInt(lector.readLine());
String tmp = lector.readLine();
for(int n = 0;n<a;n++){
if(tmp.charAt(n)=='.')continue;
for(int m = 1;m<a;m++){
int c = 1;
for(int p = n+m;p<a;p+=m)
if(tmp.charAt(p)=='*')c++;
else break;
if(c>=5){
System.out.println("yes");
return;
}
}
}
System.out.println("no");

}
}
