kod

package ThirdLesson;

import java.util.Scanner;

public class Conventor {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        double input = Double.parseDouble(scan.nextLine());
        String from = scan.nextLine();
        String to = scan.nextLine();

        if (from.equals("mm")) {
            input /= 1000;
        } else if (from.equals("cm")){
            input /= 100;
        } else if (from.equals("mi")){
            input /= 0.000621371192;
        } else if (from.equals("in")){
            input /= 39.3700787;
        } else if (from.equals("km")){
            input /= 0.001;
        } else if (from.equals("ft")){
            input /= 3.2808399;
        } else if (from.equals("yd")){
            input /= 1.0936133;
        }

        if (to.equals("mm")) {
            input *= 1000;
        } else if (to.equals("cm")){
            input *= 100;
        } else if (to.equals("mi")){
            input *= 0.000621371192;
        } else if (to.equals("in")){
            input *= 39.3700787;
        } else if (to.equals("km")){
            input *= 0.001;
        } else if (to.equals("ft")){
            input *= 3.2808399;
        } else if (to.equals("yd")){
            input *= 1.0936133;
        }
        System.out.printf("%.8f %s", input, to);

    }
}