#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void read(T &x) {
  int f = 0, ch = 0;
  x = 0;
  for (; !isdigit(ch); ch = getchar())
    if (ch == '-') f = 1;
  for (; isdigit(ch); ch = getchar()) x = x * 10 + ch - '0';
  if (f) x = -x;
}
int n;
long long a[3005];
inline long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
int main() {
  read(n);
  int ans = (0x7f7f7f7f) / 3, num = n;
  for (int i = 1; i <= n; i++) {
    read(a[i]);
    if (a[i] == 1) num--;
  }
  for (int i = 1; i <= n; i++) {
    int now = a[i];
    if (a[i] == 1) {
      ans = 1;
      break;
    }
    for (int j = i + 1; j <= n; j++) {
      now = gcd(now, a[j]);
      if (now == 1) {
        ans = ((ans) < (j - i) ? (ans) : (j - i));
        break;
      }
    }
  }
  if (ans != (0x7f7f7f7f) / 3)
    printf("%d", ans - 1 + num);
  else
    printf("-1");
  return 0;
}
