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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;
inline int _Int() {
  char INPUT[15];
  scanf("%s", INPUT);
  return atoi(INPUT);
}
long long int bigMod(long long int A, long long int P, int M) {
  long long int R = 1;
  for (A %= M; P; P >>= 1) {
    if (P & 1) R = (R * A) % M;
    A = (A * A) % M;
  }
  return R;
}
long long int bigMul(long long int A, long long int B, long long int M) {
  long long int R = 0;
  for (A %= M; B; B >>= 1) {
    if (B & 1) R = (R + A) % M;
    A = (A + A) % M;
  }
  return R;
}
unsigned long long int _pow(unsigned long long int A, int P) {
  unsigned long long int R = 1;
  for (; P; P >>= 1) {
    if (P & 1) R = (R * A);
    A = (A * A);
  }
  return R;
}
template <class T>
T GCD(T x, T y) {
  while (x) x ^= y ^= x ^= y %= x;
  return y;
}
char s[300];
void Main() {
  int n = _Int();
  scanf("%s", s + 1);
  for (int d = 1; d <= n; d++) {
    for (int i = 1; i <= n; i++) {
      if (s[i] == '*') {
        int cnt = 0, loop = 0;
        for (int j = i; loop < 5; j += d, loop++) {
          if (s[j] != '*') break;
        }
        if (loop == 5) {
          printf("yes");
          return;
        }
      }
    }
  }
  printf("no");
}
int main() {
  Main();
  return 0;
}
