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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
#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, cnt, c, sz;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 0; i < n; i++) {
    if (s[i] == '*')
      for (int j = i + 1; j < n; j++) {
        if (s[j] == '*') {
          cnt = 3;
          c = j - i;
          for (int k = j + c; k < n; k += c) {
            if (s[k] == '*') {
              cnt--;
            } else
              break;
            if (cnt == 0) {
              cout << "yes" << endl;
              return 0;
            }
          }
        }
      }
  }
  cout << "no" << endl;
}
