题解 | 二进制数1

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long a = in.nextLong();
        int number = 0;
        while(a > 0){
            number += (a & 1);
            a = a >> 1;
        }
        System.out.print(number);
    }
}