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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 read() {
  int num = 0, o = 1, r;
  char c = getchar();
  for (; c < '0' || c > '9'; c = getchar())
    if (c == '-') o = -o;
  for (; c >= '0' && c <= '9'; c = getchar()) {
    r = c - '0';
    num = num * 10 + r;
  }
  return num * o;
}
int main() {
  int n = read();
  char x[105];
  scanf("%s", x);
  int p = 0;
  int i, j, k, nn = 0, ii;
  for (i = 0; i < n; i++) {
    if (x[i] == '*') {
      for (j = i + 1; j < n; j++) {
        if (x[j] == '*') {
          nn = j - i;
          ii = 0;
          p = 1;
          for (k = i; k < n; k += nn) {
            ii++;
            if (ii == 5) break;
            if (x[k] == '.') {
              p = 0;
              break;
            }
          }
          if (p && ii == 5) goto ans;
        }
      }
    }
  }
  p = 0;
ans:
  printf("%s", p ? "yes" : "no");
  return 0;
}
