I write a java program that allow people to convert `Fahrenheit to Celsius` or `Celsius to Fahrenheit` repeatedly. Right now the code runs fine, but if I delete the two code `input=keyboardnextLine()` in the two `if statement`, the code only runs once and stops.

I don't know where I do wrong. I think the two `input=keyboardnextLine()` in the `if statements` are useless. please help me, it confuses me a lot!

```
import java.util.Scanner;

public class Q2  {
    public static void main(String[] args) {
        System.out.println("Enter\"f\" or \"F\" to convert fahrenheit to centigrade");
        System.out.println("Enter\"c\" or \"C\" to convert centigrade to fahrenheit");
        System.out.println("Enter someting else to quit");
        Scanner keyboard = new Scanner (System.in);
        String input = keyboard.nextLine();
        double fah, cel;
        while ((input.equalsIgnoreCase("f")) || (input.equalsIgnoreCase("c"))) {
            if (input.equalsIgnoreCase("f")) {
                System.out.println("Enter the temperature in fahrenheit. I will tell you the centigrade.");
                fah = keyboard.nextDouble();
                cel = 5*(fah - 32) / 9;
                System.out.println(fah+ " in centigrade is " + cel + " in fahrenheit.");
                System.out.println(" ");
                System.out.println("Enter\"f\" or \"F\" to convert fahrenheit to centigrade");
                System.out.println("Enter\"c\" or \"C\" to convert centigrade to fahrenheit");
                System.out.println("Enter someting else to quit");
                input = keyboard.nextLine();
            }

            if (input.equalsIgnoreCase("c")) {
                System.out.println("Enter the temperature in centigrade. I will tell you the fahrenheit.");
                cel = keyboard.nextDouble();
                fah = 9 * cel / 5 + 32;
                System.out.println(cel + " in centigrade is " + fah + " in fahrenheit.");
                System.out.println(" ");
                System.out.println("Enter\"f\" or \"F\" to convert fahrenheit to centigrade");
                System.out.println("Enter\"c\" or \"C\" to convert centigrade to fahrenheit");
                System.out.println("Enter someting else to quit");
                input = keyboard.nextLine();
            }
            input = keyboard.nextLine();
        }
        System.exit(0);
    }
}

```