ACMxxx定律

#include <iostream>

using namespace std;

int change(int n);

int main()
{
    int n;
    while(cin>>n && n>0)
        cout<<change(n)<<endl;

    return 0;
}

int change(int n) {
    if(n%2==1 && n!=1) return change((3*n+1)/2)+1;
    else if(n%2==0) return change(n/2)+1;
    else if(n==1) return 0;
}