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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;
inline void __CIN__() {
  ios::sync_with_stdio(false);
  cin.tie(0);
}
char buf;
inline int xint() {
  while (buf = getchar(), buf < '0' || buf > '9')
    ;
  int x = buf - '0';
  for (; buf = getchar(), buf >= '0' && buf <= '9'; x = x * 10 + buf - '0')
    ;
  return x;
}
inline long long xll() {
  while (buf = getchar(), buf < '0' || buf > '9')
    ;
  long long x = buf - '0';
  for (; buf = getchar(), buf >= '0' && buf <= '9'; x = x * 10 + buf - '0')
    ;
  return x;
}
inline string xstring() {
  while (buf = getchar(), buf == ' ' || buf == '\n')
    ;
  string x = "";
  for (x += buf; buf = getchar(), buf != ' ' && buf != '\n'; x += buf)
    ;
  return x;
}
const long long MOD = 1000000009;
long long powmod(long long a, long long b) {
  long long res = 1;
  a %= MOD;
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % MOD;
    a = a * a % MOD;
  }
  return res;
}
int main() {
  int l, data[105], i, j, k, n;
  string s;
  cin >> n;
  cin >> s;
  for (i = 0; i < n - 4; ++i)
    if (s[i] = '*') {
      for (j = 1;; ++j) {
        if (4 * j + i >= n) break;
        if (s[i + j] == '*' && s[i + 2 * j] == '*' && s[i + 3 * j] == '*' &&
            s[i + 4 * j] == '*') {
          cout << "yes" << endl;
          exit(0);
        }
      }
    }
  cout << "no" << endl;
  return 0;
}
