C++ :

#include<bits/stdc++.h>
using namespace std;
int n;
int a[60],l;
int a1[60],l1;
int main(){
	cin>>n;
	int c=n;
	while(c!=0){
		a[++l]=c%2;
		c/=2;
	}
	for(int i=1,j=l;i<j;i++,j--){
		swap(a[i],a[j]);
	}
	n-=1;
	c=n;
	while(c!=0){
		a1[++l1]=c%2;
		c/=2;
	}
	if(l1<l)
		a1[++l1]=0;
	for(int i=1,j=l1;i<j;i++,j--){
		swap(a1[i],a1[j]);
	}
	int ans=0;
	for(int i=1;i<=l;i++){
		if(a[i]!=a1[i])
			++ans;
	}
	cout<<ans;
}