#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
const int INF = INT_MAX;
const long long INFLL = (long long)1e18;
const double PI = acos(-1.0);
template <class T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
const int N = (int)1e5 + 5;
const int P = 1 << 18;
int n;
int a[2005];
int main() {
  ios::sync_with_stdio(false);
  cout.setf(ios::fixed | ios::showpoint);
  cout.precision(8);
  cin >> n;
  int cur;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (i == 0) {
      cur = a[i];
    } else
      cur = gcd(cur, a[i]);
  }
  if (cur != 1) return !printf("-1\n");
  int cnt = 0;
  for (int i = 0; i < n; i++) {
    if (a[i] != 1) cnt++;
  }
  if (cnt != n) {
    return !printf("%d\n", cnt);
  }
  int ans = INT_MAX;
  for (int i = 0; i < n; i++) {
    int cur = a[i];
    for (int j = i + 1; j < n; j++) {
      if (gcd(cur, a[j]) == 1) {
        ans = min(ans, j - i + n - 1);
      }
    }
  }
  if (ans == INT_MAX) ans = n + 1;
  cout << ans << endl;
  return 0;
}
