#include <bits/stdc++.h>
using namespace std;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}
const int mod = 1000000007, MAX = 200005, INF = 1 << 30;
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  std::ifstream in("text.txt");
  std::cin.rdbuf(in.rdbuf());
  cin.tie(0);
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<long long> A(N);
  for (int i = 0; i < N; i++) cin >> A[i];
  bool aru = false;
  for (int i = 0; i < N; i++)
    if (A[i] == 1) aru = true;
  if (aru) {
    int ans = 0;
    for (int i = 0; i < N; i++)
      if (A[i] != 1) ans++;
    cout << ans << endl;
    return 0;
  }
  int need = INF;
  for (int i = 0; i < N; i++) {
    long long g = 0;
    for (int j = i; j < N; j++) {
      g = gcd(g, A[j]);
      if (g == 1) {
        chmin(need, j - i + 1);
        break;
      }
    }
  }
  if (need == INF)
    cout << -1 << endl;
  else
    cout << need - 1 + N - 1 << endl;
}
