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

    while(i <= j){
        int reversed = reverseNumber(i);
        int number = i;
        int day = abs(number - reversed);

        if(day % k == 0) ++count;
        ++i;
    }

    return count;
}

int reverseNumber(int val){
    int result = 0;

    while(val > 0){
        result = result*10 + val%10;
        val /= 10;
    }

    return result;
}