#include <bits/stdc++.h>
using namespace std;
const int M = 100005;
int n, m, x, y;
long long a[2002];
long long sum, k;
string s, z;
vector<pair<int, int> > v;
long long gcd(long long a, long long b) {
  if (!b) return a;
  return gcd(b, a % b);
}
int main() {
  cin >> n;
  bool f = true;
  for (int i = 0; i < n; i++) {
    scanf("%lld", &a[i]);
    if (a[i] != 1) f = false;
  }
  if (f) {
    cout << 0;
    return 0;
  }
  if (n == 1) {
    if (a[0] == 1)
      cout << 0;
    else
      cout << -1;
    return 0;
  }
  int k = gcd(a[0], a[1]);
  for (int i = 2; i < n; i++) {
    k = gcd(k, a[i]);
  }
  if (k != 1) {
    cout << -1;
    return 0;
  }
  int c = 0, o = 0;
  for (int i = 0; i < n; i++) {
    if (a[i] == 1) o++;
  }
  if (o) {
    cout << n - o;
    return 0;
  }
  for (int i = 0; i < n - 1; i++) {
    if (gcd(a[i], a[i + 1]) == 1) {
      cout << n;
      return 0;
    }
  }
  int mn = 2e9;
  for (int i = 0; i < n - 1; i++) {
    k = gcd(a[i], a[i + 1]);
    int temp = k;
    for (int j = i + 2; j < n; j++) {
      k = gcd(k, a[j]);
      if (k == 1) {
        mn = min(mn, j - i - 1);
        break;
      }
    }
    for (int j = i - 1; j >= 0; j--) {
      temp = gcd(temp, a[j]);
      if (temp == 1) {
        mn = min(mn, i - j);
        break;
      }
    }
  }
  cout << n + mn;
  return 0;
}
