import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class TemperatureConverter{
    public static double c2f(double c){return c*9/5+32;}
    public static double f2c(double f){return (f-32)*5/9;}
    public static void conv(String s){
        s=s.trim();
        if(s.isEmpty()){System.out.println("输入为空，跳过。");return;}
        String[]a=s.split("\\s+");
        try{
            double v=Double.parseDouble(a[0]);
            String u=a.length>1?a[1].toUpperCase():"C";
            if(u.startsWith("C"))System.out.printf("%.1f°C=%.2f°F%n",v,c2f(v));
            else if(u.startsWith("F"))System.out.printf("%.1f°F=%.2f°C%n",v,f2c(v));
            else System.out.println("未知单位:"+u);
        }catch(Exception e){System.out.println("格式错误:"+s);}
    }
    public static void batch(String f){
        try(Scanner sc=new Scanner(new File(f))){
            System.out.println("批量转换:"+f);
            int i=0;
            while(sc.hasNextLine()){i++;System.out.print("第"+i+"行:");conv(sc.nextLine());}
            System.out.println("转换完成");
        }catch(FileNotFoundException e){System.out.println("文件不存在");}
    }
    public static void main(String[]a){
        if(a.length==0){
            Scanner sc=new Scanner(System.in);
            System.out.print("输入温度(如36.6C):");
            conv(sc.nextLine());
            sc.close();
        }else if(a.length==2)conv(a[0]+" "+a[1]);
        else if(a.length==1)batch(a[0]);
        else System.out.println("用法:\n1.java TemperatureConverter\n2.java TemperatureConverter 36.6 C\n3.java TemperatureConverter file.txt");
    }
}