Java :

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner n = new Scanner(System.in);
		int a = n.nextInt();
		reverse(a);
	}
	public static void reverse(int a) {

		if (a > 0) {
			while (a != 0) {
				int z = a % 10;
				System.out.print(z);
				a = a / 10;
			}
		} else {
			a = Math.abs(a);
			System.out.print("-");
			while (a != 0) {
				int z = a % 10;
				System.out.print(z);
				a = a / 10;
			}
		}
	}
}