Lukujono

#include <iostream>
#include <set>
using namespace std;
using ll = long long;

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int t; cin>>t;
    for (ll x; cin>>x;) {
        int ans=1;
        set<ll> seen;
        for (; x>1; ans++) {
            if (x%3==2 || seen.count(x)) {
                ans=-1;
                break;
            }
            seen.insert(x);
            x = x%3? 2*x+1 : x/3;
        }
        cout << ans << '\n';
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED