Much more optimal solution in java : `

import java.util.Scanner;

public class BeautifulDaysAtTheMovies {

public static int beautifulDays(int i, int j, int k) {
    int count = 0;

    for (int day = i; day <= j; day++) {
        int reversed = reverseNumber(day);
        if (Math.abs(day - reversed) % k == 0) {
            count++;
        }
    }

    return count;
}

private static int reverseNumber(int num) {
    int reversed = 0;
    while (num > 0) {
        reversed = reversed * 10 + num % 10;
        num /= 10;
    }
    return reversed;
}

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    // Read input values
    int i = scanner.nextInt();
    int j = scanner.nextInt();
    int k = scanner.nextInt();

    // Compute and print the number of beautiful days
    System.out.println(beautifulDays(i, j, k));

    scanner.close();
}

} `