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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;
set<long long>::iterator it;
vector<long long>::iterator it1;
struct stc {
  int fir, sc;
} input[1000];
bool comp(stc a, stc b) { return a.fir < b.fir; }
int main() {
  long long n, i, j, k, it, ans, f, len;
  string s;
  while (cin >> n) {
    cin >> s;
    len = s.size();
    f = 1;
    if (len < 5)
      cout << "no\n";
    else {
      for (j = 0; j < len; j++) {
        if (s[j] == '*') {
          ans = 1;
          for (i = j + 1; i < len; i++) {
            if (s[i] == '*') {
              ans = 2;
              for (k = i + (i - j); k < len; k += (i - j)) {
                if (s[k] == '*') {
                  ans++;
                } else {
                  f = 1;
                  break;
                }
                if (ans == 5) {
                  f = 0;
                  break;
                }
              }
            }
            if (!f) break;
          }
        }
        if (!f) break;
      }
      if (!f)
        cout << "yes\n";
      else
        cout << "no\n";
    }
  }
  return 0;
}
