题解 | 清楚姐姐买竹鼠

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);
        // 注意 hasNext 和 hasNextLine 的区别
        long a = in.nextLong();
        long b = in.nextLong();
        long x = in.nextLong();
        if (a * 3 < b) {
            System.out.println(a * x);
            return;
        }
        if (a > b) {
            long bbNum = x / 3;
            if (x % 3 == 0) {
                System.out.println((bbNum) * b);
            } else {
                System.out.println((bbNum + 1) * b);
            }
            return;
        }
        long bNum = x / 3;
        long aNum = x % 3;
        // System.out.println(aNum + " " + bNum);
        System.out.println(a * aNum + b * bNum);
    }
}