逆推30pts 求助！

#include<bits/stdc++.h>
using namespace std;
	long long a;
	int b;
int main(){
	cin>>a;
	if(a%2!=0)b++;
	while(a!=1){
		b++;
		if(a%2==0)a/=2;
		else if(((a+1)/2)%2==0)a++;
		else a--;
	//	cout<<a<<endl;
	}
	cout<<b;
	return 0;}