#include<bits/stdc++.h>
using namespace std;
const int N=1000;
int main(){
int n;
cin>>n;
int ans=0;
for(int i=1;i<=N;i++){
    if(n==1){
        ans++;
        break;
    }
    if(n%2==1){
        ans++;
        n=(n-1)/2;
    }
    else{
        n=n/2;
    }
}
cout<<ans;

}
 

C++ :

#include<bits/stdc++.h>
using namespace std;
int ans;

int main(){
	int n;
	cin>>n;
	ans=0;
	while(n!=1){
		ans+=(n%2);
		n/=2;
	}
	cout<<(ans+1);
	
	return 0;
}

Python :

# coding=utf-8
n=int(input())
s=0
while n>0:
    s+=n%2
    n=n//2
print(s)

s=''
while x>0:
    s=str(x%2)+s
    x=x//2
t=0
for i in s:
    if i=='1':
        t+=1
print(t)