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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;
int gcd(int a, int b) {
  int r;
  while (b != 0) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int getBit(int s, int i) { return (s >> i) & 1; }
int onBit(int s, int i) { return s | (int(1) << i); }
int offBit(int s, int i) { return s & (~(int(1) << i)); }
int cntBit(int s) { return __builtin_popcount(s); }
int sqr(int x) { return x * x; };
const int MOD = 1e9 + 7;
const int SIZE = 1e6 + 10;
const int DX[4] = {-1, 1, 0, 0};
const int DY[4] = {0, 0, 1, -1};
string s;
int n;
bool isGood(int len) {
  for (int start = (0), _b = (n); start < _b; ++start)
    if (s[start] == '*') {
      int cnt = 0;
      int i = start;
      while (i < n && s[i] == '*') {
        cnt++;
        i += len;
      }
      if (cnt >= 5) return true;
    }
  return false;
}
int main() {
  scanf("%d\n", &n);
  cin >> s;
  for (int len = (1), _b = (n - 1); len <= _b; len++)
    if (isGood(len)) {
      cout << "yes";
      return 0;
    }
  cout << "no";
  return 0;
}
