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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>
using namespace std;
template <class C>
void mini(C& a4, C b4) {
  a4 = min(a4, b4);
}
template <class C>
void maxi(C& a4, C b4) {
  a4 = max(a4, b4);
}
template <class T1, class T2>
ostream& operator<<(ostream& out, pair<T1, T2> pair) {
  return out << "(" << pair.first << ", " << pair.second << ")";
}
template <class A, class B, class C>
struct Triple {
  A first;
  B second;
  C third;
};
template <class T>
void ResizeVec(T&, vector<long long>) {}
template <class T>
void ResizeVec(vector<T>& vec, vector<long long> sz) {
  vec.resize(sz[0]);
  sz.erase(sz.begin());
  if (sz.empty()) {
    return;
  }
  for (T& v : vec) {
    ResizeVec(v, sz);
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(10);
  double beg_clock = 1.0 * clock() / CLOCKS_PER_SEC;
  long long n;
  cin >> n;
  ;
  string s;
  cin >> s;
  ;
  s = ' ' + s;
  for (long long i = (1); i <= (n); ++i) {
    for (long long j = (i + 1); j <= (n); ++j) {
      vector<long long> cands{i, j};
      for (long long tr = 0; tr < (3); ++tr) {
        cands.push_back(cands.back() + j - i);
      }
      long long bad = 0;
      for (auto x : cands) {
        if (x > n || s[x] == '.') {
          bad = 1;
        }
      }
      if (!bad) {
        cout << "yes\n";
        return 0;
      }
    }
  }
  cout << "no\n";
  return 0;
}
