参考答案：

#include<iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    int sum = 0;
    while (n != 1)
    {
        if (n & 1) n = n * 3 + 1;
        else n /= 2;
        ++sum;
    }
    cout << sum << endl;

    return 0;
}