#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e7;
int gcd(int a, int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
int main() {
  int n, ans = INT_MAX, count = 0;
  cin >> n;
  vector<int> v(n);
  for (int i = 0; i < n; i++) {
    cin >> v[i];
    count += (v[i] == 1);
  }
  if (count > 0) {
    cout << n - count << endl;
  } else {
    vector<vector<int>> dp(n, vector<int>(n));
    for (int i = 0; i < n; i++) dp[i][i] = v[i];
    for (int i = 0; i < n; i++)
      for (int j = i + 1; j < n; j++) dp[i][j] = gcd(v[j], dp[i][j - 1]);
    for (int i = 0; i < n; i++)
      for (int j = i; j < n; j++)
        if (dp[i][j] == 1) ans = min(ans, j - i);
    if (ans == INT_MAX)
      cout << -1 << endl;
    else
      cout << ans + n - 1 << endl;
  }
  return 0;
}
