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 5
****.

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;
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;
}
