import java.util.Scanner;

// 温度转换：摄氏 ↔ 华氏
public class TemperatureConverter {
    // 摄氏转华氏
    public static double c2f(double c) {
        return c * 9 / 5 + 32;
    }
    // 华氏转摄氏
    public static double f2c(double f) {
        return (f - 32) * 5 / 9;
    }

    public static void main(String[] args) {
        if (args.length >= 1) {
            runWithArgs(args);
            return;
        }
        Scanner sc = new Scanner(System.in);
        System.out.print("输入温度和单位（如 36.6 C 或 97 F）：");
        String line = sc.nextLine().trim();
        sc.close();
        if (line.isEmpty()) {
            System.out.println("输入为空，退出。");
            return;
        }
        String[] parts = line.split(" ");
        try {
            double val = Double.parseDouble(parts[0]);
            String unit = parts.length > 1 ? parts[1].toUpperCase() : "C";
            if (unit.startsWith("C")) {
                double f = c2f(val);
                System.out.printf("%.2f °C = %.2f °F%n", val, f);
            } else if (unit.startsWith("F")) {
                double c = f2c(val);
                System.out.printf("%.2f °F = %.2f °C%n", val, c);
            } else {
                System.out.println("单位不对，用 C 或 F。");
            }
        } catch (NumberFormatException e) {
            System.out.println("输入不对，像这样：36.6 C");
        }
    }

    // 处理命令行参数
    private static void runWithArgs(String[] args) {
        try {
            double val = Double.parseDouble(args[0]);
            String unit = args.length > 1 ? args[1].toUpperCase() : "C";
            if (unit.startsWith("C")) {
                double f = c2f(val);
                System.out.printf("%.2f °C = %.2f °F%n", val, f);
            } else if (unit.startsWith("F")) {
                double c = f2c(val);
                System.out.printf("%.2f °F = %.2f °C%n", val, c);
            } else {
                System.out.println("单位不对，用 C 或 F。");
            }
        } catch (NumberFormatException e) {
            System.out.println("参数不对，像这样：java TemperatureConverter 36.6 C");
        }
    }
}