#include <bits/stdc++.h>
const double EPS = 1e-24;
const long long int MOD = 1000000007ll;
const double PI = 3.14159265359;
int INF = 2147483645;
template <class T>
T Max2(T a, T b) {
  return a < b ? b : a;
}
template <class T>
T Min2(T a, T b) {
  return a < b ? a : b;
}
template <class T>
T Max3(T a, T b, T c) {
  return Max2(Max2(a, b), c);
}
template <class T>
T Min3(T a, T b, T c) {
  return Min2(Min2(a, b), c);
}
template <class T>
T Max4(T a, T b, T c, T d) {
  return Max2(Max2(a, b), Max2(c, d));
}
template <class T>
T Min4(T a, T b, T c, T d) {
  return Min2(Min2(a, b), Max2(c, d));
}
template <class T>
void Swap(T& a, T& b) {
  T temp;
  temp = a;
  a = b;
  b = temp;
}
using namespace std;
int main() {
  std::ios::sync_with_stdio(false);
  int n;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 1; i < 25; i++) {
    for (int j = 0; j + 4 * i < 100; j++) {
      if (s[j] == s[j + i] && s[j + i] == s[j + 2 * i] &&
          s[j + 2 * i] == s[j + 3 * i] && s[j + 3 * i] == s[j + 4 * i] &&
          s[j] == '*') {
        cout << "yes";
        return 0;
      }
    }
  }
  cout << "no";
  return 0;
  return 0;
}
