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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>
double const EPS = 3e-8;
using namespace std;
template <class T>
T gcd(T a, T b) {
  return (b != 0 ? gcd<T>(b, a % b) : a);
}
template <class T>
T lcm(T a, T b) {
  return (a / gcd<T>(a, b) * b);
}
template <class T>
inline bool read(T &x) {
  int c = getchar();
  int sgn = 1;
  while (~c && c < '0' || c > '9') {
    if (c == '-') sgn = -1;
    c = getchar();
  }
  for (x = 0; ~c && '0' <= c && c <= '9'; c = getchar()) x = x * 10 + c - '0';
  x *= sgn;
  return ~c;
}
string inp;
int main() {
  int n = ({
    int a;
    read(a);
    a;
  });
  cin >> inp;
  int i, sz = n, j;
  bool ok = 1;
  for (i = sz - 1; i >= 3 && ok; i--) {
    if (inp[i] == '.') continue;
    for (j = 1; j <= 100 && ok; j++) {
      int now = i;
      int cnt = 0;
      while (1) {
        now -= j;
        if (now < 0) break;
        if (inp[now] == '.') break;
        cnt++;
        if (cnt >= 4) {
          ok = 0;
          break;
        }
      }
    }
  }
  puts(ok ? "no" : "yes");
  return 0;
}
