20
.*..*...*....*.....*
 97
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 5
*.***
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 72
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 89
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 6
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 54
...***.*...****.*..****....*..**..**..***.*..**...**..
 100
****************************************************************************************************
 53
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 21
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 41
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 31
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 10
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 69
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 57
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 17
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 56
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 99
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 42
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 99
***************************************************************************************************
 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 p1 {

    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter ps = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
    static StringTokenizer st;

    public static void main (String[] args) throws IOException {
        int n = readInt();
        boolean good = false;
        char[] in = readLine().toCharArray();
        for (int i = 0; i < n; i++) {
            if (in[i] == '.')
                continue;
            for (int d = 1; d < n; d++) {
                int c;
                for (c = 1; i + d*c < n && in[i + d*c] == '*'; c++);
                c--;
                if (c >= 4) {
//                  System.out.println(i + " " + d + " " + c);
                    good = true;
                }
            }
        }
        if (good)
            System.out.println("yes");
        else
            System.out.println("no");
    }

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

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

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

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

    static char readCharacter () throws IOException {
        return next().charAt(0);
    }

    static String readLine () throws IOException {
        return br.readLine().trim();
    }
}
