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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;
long long int gcd(long long int a, long long int b) {
  return (b == 0) ? a : gcd(b, a % b);
}
long long int lcm(long long int a, long long int b) {
  return (a * b) / gcd(a, b);
}
long long int modpow(long long int a, long long int n, long long int mod) {
  long long int res = 1;
  while (n) {
    if (n & 1) res = (res * a) % mod;
    a = (a * a) % mod;
    n >>= 1;
  }
  return res;
}
long long int lpow(long long int a, long long int n) {
  long long int res = 1;
  while (n) {
    if (n & 1) res *= a;
    a *= a;
    n >>= 1;
  }
  return res;
}
int n;
int a[110];
void Scan() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    char c;
    cin >> c;
    a[i] = ((c == '*') ? 1 : 0);
  }
  return;
}
int Out() {
  for (int i = 0; i < n; i++) {
    if (a[i] == 1)
      for (int d = 1; d <= n; d++) {
        int f = 0;
        for (int j = 1; j <= 4; j++) {
          int p = j * d;
          if (i + p < n && a[i + p] == 1) f++;
        }
        if (f == 4) {
          return 1;
        }
      }
  }
  return 0;
}
int main() {
  Scan();
  if (Out())
    cout << "yes\n";
  else
    cout << "no\n";
  return 0;
}
