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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>
inline int two(int n) { return 1 << n; }
inline int test(int n, int b) { return (n >> b) & 1; }
inline void set_bit(int& n, int b) { n |= two(b); }
inline void unset_bit(int& n, int b) { n &= ~two(b); }
inline int last_bit(int n) { return n & (-n); }
inline int ones(int n) {
  int res = 0;
  while (n && ++res) n -= n & (-n);
  return res;
}
long long int gcd(long long int a, long long int b) {
  return (a ? gcd(b % a, a) : b);
}
long long int modPow(long long int a, long long int b, long long int MOD) {
  long long int x = 1, y = a;
  while (b > 0) {
    if (b % 2 == 1) {
      x = (x * y) % MOD;
    }
    b /= 2;
    y = (y * y) % MOD;
  }
  return x;
}
long long int modInverse(long long int a, long long int p) {
  return modPow(a, p - 2, p);
}
using namespace std;
string str;
vector<int> v;
map<int, int> mymap;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, i, j, k, diff;
  cin >> n;
  cin >> str;
  for (diff = 1; diff <= n; diff++) {
    for (j = 0; j < n; j++) {
      long long int ctr = 1;
      for (k = j + diff; k < n; k += diff) {
        if (str[k] == '*')
          ctr++;
        else
          break;
        if (ctr >= 5) {
          cout << "yes";
          return 0;
        }
      }
      if (ctr >= 5) {
        cout << "yes";
        return 0;
      }
    }
  }
  cout << "no";
  return 0;
}
