How do I make this that the input will no longer be 0?

import java.util.Scanner;
public class Main2
{
	public static void main(String[] args) {
	    int choice,firstnum,secondnum;
        Scanner sc = new Scanner(System.in);

	 
	   while(true) {
    		System.out.println("==================================");
    		System.out.println("  S E L E C T  O P E R A T I O N");
    		System.out.println("==================================");
    		System.out.println(" [1] --> Computation of Power");
                System.out.println("----------------------------------");
    		System.out.println("Enter choice:");
    		choice = sc.nextInt();
    		System.out.println("Enter first number:");
    		firstnum = sc.nextInt();
    		System.out.println("Enter second number:");
    		secondnum = sc.nextInt();
    		
    		}
    		else if(choice == 1){
    		   System.out.println("Result: "+(firstnum/secondnum));
    		 
    		}