20
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 97
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 5
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 72
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 89
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 6
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 54
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 100
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 53
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 90
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 10
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 69
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 99
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 98
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 99
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 51
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 71
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 100
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 7
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 67
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 6
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 75
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 13
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 99
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 99
***************************************************************************************************
 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;
const long double eps = 1e-9;
const int inf = (1 << 30) - 1;
const long long inf64 = ((long long)1 << 62) - 1;
const long double pi = acos(-1);
template <class T>
T sqr(T x) {
  return x * x;
}
template <class T>
T abs(T x) {
  return x < 0 ? -x : x;
}
const int MAXN = 200;
const int k = 4;
int a[MAXN];
int main() {
  ios_base::sync_with_stdio(0);
  int n;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 0; i < n; ++i) {
    a[i] = (s[i] == '*' ? 1 : 0);
  }
  for (int d = 1; d < n; ++d) {
    for (int i = 0; i + k * d < n; ++i) {
      bool key = true;
      for (int j = 0; j <= k; ++j) {
        if (a[i + j * d] == 0) {
          key = false;
          break;
        }
      }
      if (key) {
        cout << "yes" << endl;
        return 0;
      }
    }
  }
  cout << "no" << endl;
  return 0;
}
