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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.BufferedReader;
import java.io.InputStreamReader;
import java.util.StringTokenizer;


public class A {
	public static void main(String[] args) throws Exception{
		int n = readInt();
		boolean platform[] = new boolean[n];
		String s = readString();
		for(int i = 0; i < n; i++){
			platform[i] = s.charAt(i) == '*';
		}
		boolean pos = false;
		for(int i = 1; i < n; i++){
			for(int j = 0; j < n; j++){
				if(possible(i, j, platform, n)){
					pos = true;
				}
			}
		}
		if(pos){
			System.out.println("yes");
		}
		else{
			System.out.println("no");
		}
	}

	private static boolean possible(int step, int start, boolean[] platform, int n) {
		int cur = start;
		if(!platform[cur]){
			return false;
		}
		for(int i = 0; i < 4; i++){
			cur+=step;
			if(cur >= n){
				return false;
			}
			if(!platform[cur]){
				return false;
			}
		}
		return true;
	}

	static BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
	static StringTokenizer st = new StringTokenizer(" ");
	static String readString() throws Exception{
		while(!st.hasMoreTokens()){
			st = new StringTokenizer(stdin.readLine());
		}
		return st.nextToken();
	}
	static int readInt() throws Exception {
		return Integer.parseInt(readString());
	}
	static long readLong() throws Exception {
		return Long.parseLong(readString());
	}
}
