20
.*..*...*....*.....*
 97
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 5
*.***
 4
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 11
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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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 87
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 90
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 55
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 21
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 41
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 31
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 64
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 10
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 99
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 69
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 99
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 98
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 57
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 64
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 17
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 100
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 11
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 1
.
 100
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 56
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 99
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 10
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 51
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 17
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 97
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 42
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 5
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 42
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 71
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 5
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 99
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 42
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 10
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 1
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 5
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 16
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 100
*.......................*.......................*.......................*.......................*...
 7
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 58
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 67
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 99
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 6
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 11
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 15
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 75
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 45
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 13
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 5
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 100
*****...............................................................................................
 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;
long long EPS = 1000000007;
long double PI = 3.14159265358979323846;
const int MAXN = 1000010;
long long abss(long long h) { return max(h, -h); }
long double fabss(long double h) { return max(h, -h); }
long long ceill(long long x, long long y) {
  if (x % y != 0) {
    return (x / y) + 1;
  }
  return x / y;
}
string itos(long long num) {
  string str = "";
  if (num == 0) {
    return "0";
  }
  while (num != 0) {
    str += ((num % 10) + '0');
    num /= (long long)10;
  }
  reverse(str.begin(), str.end());
  return str;
}
long long n, m, k, r, t;
int a[MAXN];
long long b[10][10];
vector<int> p[MAXN];
map<int, int> ma;
string need[MAXN];
int main() {
  int n;
  cin >> n;
  string str;
  cin >> str;
  for (int i = 0; i < str.size(); i++) {
    for (int j = 1; j < str.size(); j++) {
      int count = 0;
      int index = i;
      while (index < str.size()) {
        if (str[index] == '*') {
          count++;
          index += j;
        } else {
          break;
        }
      }
      if (count >= 5) {
        cout << "yes";
        return 0;
      }
    }
  }
  cout << "no";
}
