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)