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***************************************************************************************************
 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>
#pragma comment(linker, "/STACK:128777216")
using namespace std;
const long long LINF = 1000000000000000000LL;
const int INF = 1000000000;
const long double eps = 1e-9;
const long double PI = 3.1415926535897932384626433832795l;
void prepare(string s) {
  if (s.length() != 0) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
  }
}
const int NMAX = 155;
int n;
char s[NMAX];
void read() {
  scanf("%d\n", &n);
  scanf("%s", s);
}
void solve() {
  for (int i = 0; i < (int)(n); i++) {
    if (s[i] == '*') {
      for (int j = 1; j <= n; j++) {
        bool ok = true;
        int c = 0;
        for (int k = i; c < 5 && k < n; k += j, c++) {
          ok = ok && s[k] == '*';
        }
        if (ok && c == 5) {
          printf("yes\n");
          return;
        }
      }
    }
  }
  printf("no\n");
}
int main() {
  prepare("");
  read();
  solve();
  return 0;
}
