#include <bits/stdc++.h>
using namespace std;
int n, a[2006];
int one, g, mn = 1e9;
int gcd(int _a, int _b) { return _b == 0 ? _a : gcd(_b, _a % _b); }
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
    g = gcd(g, a[i]);
    if (a[i] == 1) one++;
  }
  if (one != 0) {
    printf("%d\n", n - one);
    return 0;
  }
  if (g != 1) {
    puts("-1");
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    int b = a[i];
    for (int j = i + 1; j <= n; j++) {
      b = gcd(b, a[j]);
      if (b == 1) {
        mn = min(mn, j - i);
        break;
      }
    }
  }
  printf("%d\n", mn + n - 1);
  return 0;
}
