20
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 97
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 5
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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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 17
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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
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 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
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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>
template <class T>
inline bool rd(T &ret) {
  char c;
  int sgn;
  if (c = getchar(), c == EOF) return 0;
  while (c != '-' && (c < '0' || c > '9')) c = getchar();
  sgn = (c == '-') ? -1 : 1;
  ret = (c == '-') ? 0 : (c - '0');
  while (c = getchar(), c >= '0' && c <= '9') ret = ret * 10 + (c - '0');
  ret *= sgn;
  return 1;
}
template <class T>
inline void pt(T x) {
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  if (x > 9) pt(x / 10);
  putchar(x % 10 + '0');
}
using namespace std;
const int NNN = 100;
char a[105];
int hehe;
int main() {
  int n;
  scanf("%d%s", &n, a);
  bool flag = false;
  for (int i = 0; i < n && !flag; i++) {
    if (a[i] == '*') {
      for (int j = 1; j < n; j++) {
        if (i + j * 4 > n) break;
        if (a[i + j] == '*' && a[i + j * 2] == '*' && a[i + j * 3] == '*' &&
            a[i + j * 4] == '*') {
          flag = true;
          break;
        }
      }
    }
  }
  if (flag)
    puts("yes");
  else
    puts("no");
  return 0;
}
