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 100
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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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ProblemA {
    BufferedReader rd;

    private ProblemA() throws IOException {
        rd = new BufferedReader(new InputStreamReader(System.in));
        compute();
    }

    private void compute() throws IOException {
        rd.readLine();
        String s = rd.readLine();
        int n = s.length();
        for(int i=1;i<25;i++) {
            for(int j=0;j<n;j++) {
                if(s.charAt(j)=='*') {
                    int k = j;
                    int p = 0;
                    while(p<4) {
                        k += i;
                        if(k >= n) {
                            break;
                        }
                        if(s.charAt(k) != '*') {
                            break;
                        }
                        p++;
                    }
                    if(p == 4) {
                        out("yes");
                        return;
                    }
                }
            }
        }
        out("no");
    }

    private static void out(Object x) {
        System.out.println(x);
    }

    public static void main(String[] args) throws IOException {
        new ProblemA();
    }
}
