#include <bits/stdc++.h>
using namespace std;
long long a[2010];
int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
int main() {
  int n;
  scanf("%d", &n);
  int cnt = 0, ans = 0x3f3f3f3f;
  scanf("%lld", a + 1);
  if (a[1] == 1) cnt++;
  long long g = a[1];
  if (n == 1 && a[n] == 1) {
    cout << 0 << endl;
    return 0;
  }
  for (int i = 2; i <= n; i++) {
    scanf("%lld", a + i);
    if (a[i] == 1) cnt++;
    g = gcd(g, a[i]);
  }
  if (g != 1) {
    cout << -1 << endl;
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    long long temp = a[i];
    for (int j = i + 1; j <= n; j++) {
      int len;
      temp = gcd(temp, a[j]);
      if (temp == 1) {
        len = j - i;
        ans = min(len, ans);
        break;
      }
    }
    if (ans == 1) break;
  }
  printf("%d\n", ans + n - 1 - cnt);
}
