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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>
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;
}
