#include <bits/stdc++.h>
const int N = 3e5 + 5;
using namespace std;
vector<int> mv[N];
int prime[N], a[N], f[N], d[N], Cnt[N], cnt[N], mobius[N];
int n;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  for (int i = 2; i < N; i++) {
    if (!prime[i] && i != 1)
      for (int j = i; j < N; j += i) prime[j] = i;
    int cur = i;
    mobius[i] = 1;
    f[i] = 1;
    while (prime[cur]) {
      int pri = prime[cur], cnt = 0;
      while (prime[cur] == pri) cur /= pri, cnt++;
      f[i] *= pri;
      if (cnt > 1) mobius[i] = 0;
      mobius[i] = -mobius[i];
    }
  }
  f[1] = 1;
  mobius[1] = 1;
  for (int i = 1; i < N; i++) {
    if (mobius[i])
      for (int j = i; j < N; j += i)
        if (mobius[j]) mv[j].push_back(i);
  }
  queue<int> mq;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    a[i] = f[a[i]];
    for (auto v : mv[a[i]]) Cnt[v]++;
    if (!d[a[i]]) {
      mq.push(a[i]);
      d[a[i]] = 2;
    }
  }
  for (int i = 1; i < N; i++) {
    if (mobius[i])
      for (int j = i; j < N; j += i) cnt[j] += mobius[i] * Cnt[i];
  }
  while (mq.size()) {
    int u = mq.front();
    mq.pop();
    for (auto v : mv[u]) {
      if (!d[v] && cnt[u / v]) {
        d[v] = d[u] + 1;
        mq.push(v);
      }
    }
  }
  cout << d[1] - 1;
}
