Untitled

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Introduce una palabra: ");
        String palabra = scanner.nextLine();

        for (int i = palabra.length() - 1; i >= 0; i--) {
            char letra = palabra.charAt(i);
            System.out.println(letra);
        }
    }
}