#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s >> s;
  for (int i = 1; i < s.length() / 4 + 1; ++i) {
    for (int j = 0; j < s.length() - i * 4; ++j) {
      int count = 0;
      for (int k = j; k < s.length(); k += i) {
        if (s[k] == '*') {
          ++count;
          if (count > 4) {
            cout << "yes" << endl;
            return 0;
          }
        } else
          count = 0;
      }
    }
  }
  cout << "no" << endl;
  return 0;
}
