VERY VERY IMP THING IN PROGRAMMING

Question: https://www.hackerrank.com/challenges/halloween-party
Ans:
 When we store the answer in different datatype, always remember to typecast it


WRONG ANS:

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        in.nextLine();
        for(int i=0;i<n;i++){
            int k = in.nextInt();
            long ans = 0;
            ans = (k/2)*(k-(k/2));
            System.out.println(ans);
            if(i!=n-1)
            in.nextLine();
        }
    }
}

CORRECT ANS:
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        in.nextLine();
        for(int i=0;i<n;i++){
            int k = in.nextInt();
            long ans = 0;
            ans = (long)(k/2)*(k-(k/2));        // When we store the answer in different datatype, always remember to typecast it
            System.out.println(ans);
            if(i!=n-1)
            in.nextLine();
        }
    }
}