按位与

#include<iostream>

int main(int argc, char const *argv[])
{
    int n,c = 0;
    std::cin >> n;
    while (n!=0)
    {
        if (n & 1)
        {
            c++;
        }
        n /= 2;
    }
    std::cout << c << std::endl;
    return 0;
}