#include <bits/stdc++.h>
using namespace std;
long long power(long long a, long long n) {
  a %= 1000000007;
  if (n == 1) return a;
  if (n == 0) return 1;
  if (n % 2)
    return (a * (power((a * a) % 1000000007, n / 2) % 1000000007)) % 1000000007;
  return power((a * a) % 1000000007, n / 2) % 1000000007;
}
const long long inf = (long long)1e18;
long long inverse(long long x) { return power(x, 1000000007 - 2) % 1000000007; }
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n, ans = 0;
  string s;
  cin >> n >> s;
  for (long long i = 0; i < n; ++i) {
    if (s[i] == '.') continue;
    for (long long d = 1; d < 101; ++d) {
      long long fo = 1;
      for (long long j = 1; j < 5; ++j)
        if (i + j * d >= n || s[i + j * d] == '.') fo = 0;
      if (fo) ans = 1;
    }
  }
  if (ans)
    cout << "yes\n";
  else
    cout << "no\n";
  return 0;
}
