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****.

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#include <bits/stdc++.h>
void dout() { printf("\n"); }
template <typename Head, typename... Tail>
void dout(Head H, Tail... T) {}
using namespace std;
struct Input {
  double beg;
  int n;
  string s;
  bool read() {
    if (scanf("%d", &n) <= 0) return false;
    cin >> s;
  }
  void init(const Input &input) { *this = input; }
};
struct Output : Input {
  bool res = false;
  void write() {
    if (res)
      printf("yes");
    else
      printf("no");
  }
  virtual void solve() {}
  virtual void clear() { *this = Output(); }
};
struct Solution : Output {
  int a[105];
  void solve() {
    memset(a, 0, sizeof(a));
    for (int i = 0; i < n; ++i) {
      if (s[i] == '.') continue;
      for (int j = 0; j < i; ++j) {
        if (s[j] == '.') continue;
        a[i - j]++;
        if (a[i - j] == 4) {
          dout("-> ", i - j, i);
          bool check = true;
          for (int z = 0; z < 5; ++z) {
            dout(i - z * (i - j), " ", s[i - z * (i - j)]);
            if (s[i - z * (i - j)] != '*') {
              check = false;
              break;
            }
          }
          if (check) {
            res = true;
            return;
          }
        }
      }
    }
  }
  void clear() { *this = Solution(); }
};
Solution _sol;
int main() {
  _sol.read();
  _sol.solve();
  _sol.write();
  return 0;
}
