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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>
#pragma comment(linker, "/STACK:256000000")
using namespace std;
const long double PI = 3.14159265358979323846;
const long double gammama = 0.57721566490153286060;
const long double eps = 1e-5;
const int INF = 1000 * 1000 * 1000 + 1;
const long long LINF = (long long)1000 * 1000 * 1000 * 1000 * 1000 * 1000;
const long long mod = 1000 * 1000 * 1000 + 7;
const long long N = 1001;
void solve() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  int res = 0;
  for (int d = 1; d < n; ++d) {
    vector<int> a(n, 0);
    int m = 0;
    for (int i = 0; i < n; ++i) {
      if (s[i] == '.')
        a[i] = 0;
      else {
        if (i - d >= 0) {
          a[i] = a[i - d] + 1;
        } else
          a[i] = 1;
      }
      m = max(m, a[i]);
    }
    res = max(res, m);
  }
  if (res >= 5)
    cout << "yes";
  else
    cout << "no";
  cout << endl;
}
int main() {
  solve();
  return 0;
}
