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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 n, t, s, f;
int a[102];
bool go(int from, int step) {
  if (a[from] && (from + step < n && a[from + step]) &&
      (from + 2 * step < n && a[from + 2 * step]) &&
      (from + 3 * step < n && a[from + 3 * step]) &&
      (from + 4 * step < n && a[from + 4 * step]))
    return true;
  else
    return false;
}
int main(int argc, const char* argv[]) {
  ios::sync_with_stdio(0);
  cin >> n;
  char x;
  for (int i = 0; i < n; i++) {
    cin >> x;
    if (x == '*') a[i] = 1;
  }
  int st = 0;
  while (a[st] != 1) st++;
  while (st + 2 < n) {
    if (a[st])
      for (int i = 1; i <= (n - st + 1) / 4; i++) {
        if (go(st, i)) {
          cout << "yes\n";
          return 0;
        }
      }
    st++;
  }
  cout << "no\n";
  return 0;
}
