20
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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;
inline void read(int &x) {
  char ch;
  int t = 0;
  x = 0;
  for (ch = getchar(); ch < '0' || ch > '9'; ch = getchar())
    if (ch == '-') t = 1;
  for (; ch >= '0' && ch <= '9'; x = x * 10 + ch - 48, ch = getchar())
    ;
  if (t) x = -x;
}
const int N = 105, mod = 1e9 + 7;
char str[N];
int main() {
  int n, i, j, k, l, r, p, T, m;
  int s, t, x, y, a, b;
  while (~scanf("%d", &n)) {
    scanf("%s", str);
    for (i = 0; i < n; i++) {
      for (j = 1; j < n; j++) {
        for (k = 0; k < 5; k++)
          if (i + k * j >= n || str[i + k * j] != '*') break;
        if (k == 5) goto out;
      }
    }
  out:
    if (k == 5)
      printf("yes\n");
    else
      printf("no\n");
  }
  return 0;
}
