Calculator (if , else if) Statement

import java.util.Scanner;

public class Cal {

public static void main(String[] args) {
// TODO Auto-generated method stub
// let,s Start
int a;
int num1;
int num2;
int ans;

Scanner scan = new Scanner(System.in);

System.out.println("1 : Addition");
System.out.println("2 : Substraction");
System.out.println("3 : Multiplication");
System.out.println("4 : Devision");
//in ko show krwanay kay leya humy 1 a variable lena ho ga//
a=scan.nextInt();

if(a==1) {
System.out.println("ENTER YOUR FIRST NUMBER");
num1=scan.nextInt();
System.out.println("ENTER YOUR SECOND NUMBER");
num2=scan.nextInt();
ans=num1+num2;
System.out.println(ans);
}

if(a==2) {
System.out.println("ENTER YOUR FIRST NUMBER");
num1=scan.nextInt();
System.out.println("ENTER YOUR SECOND NUMBER");
num2=scan.nextInt();
ans=num1-num2;
System.out.println(ans);
}

if(a==3) {
System.out.println("ENTER YOUR FIRST NUMBER");
num1=scan.nextInt();
System.out.println("ENTER YOUR SECOND NUMBER");
num2=scan.nextInt();
ans=num1*num2;
System.out.println(ans);
}

if(a==4) {
System.out.println("ENTER YOUR FIRST NUMBER");
num1=scan.nextInt();
System.out.println("ENTER YOUR SECOND NUMBER");
num2=scan.nextInt();
ans=num1/num2;
System.out.println(ans);
}



}

}