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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;
  cin >> n;
  int *mas = new int[n];
  string ch;
  cin >> ch;
  int i;
  for (i = 0; i < n; i++) {
    if (ch[i] == '*')
      mas[i] = 1;
    else
      mas[i] = 0;
  }
  int res, pos;
  res = 0;
  pos = -1;
  for (i = 0; i < n; i++)
    if (mas[i]) {
      pos = i;
      break;
    }
  int step = 1;
  int count = 0;
  if (pos != -1) {
    while (pos + 3 * step < n) {
      count = 0;
      for (i = pos; i < n - step; i += step)
        if (mas[i] == mas[i + step]) {
          count++;
          if (count == 4) {
            res = 1;
            break;
          }
        }
      if (res) break;
      step++;
      if (pos + 3 * step >= n) {
        int j;
        for (j = pos + 1; j < n; j++)
          if (mas[j]) {
            pos = j;
            step = 1;
            count = 0;
            break;
          }
      }
    }
  }
  if (res)
    cout << "yes";
  else
    cout << "no";
  delete[] mas;
  return 0;
}
