In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.

Input: Consider Input: Question: To calculate the number of different genotypes in any allelic series the formula is applied: 
 Options:  <1> (n-1) / 2. <2> n x (n + 1) / 2. <3> n x (n-1) / 2. <4> (n-1) x (n + 1) / 2. <5> (2n-1) / 2.

Output: 2


Input: Consider Input: Question: The main pharmacological treatment for obsessive-compulsive disorder or OCD is: 
 Options:  <1> Dopamine agonists. <2> NMDA receptor blockers. <3> Inhibitors of monoamine oxidase or MAOIs. <4> Selective serotonin or 5-HT reuptake inhibitors. <5> Neuroleptics

Output: 4


Input: Consider Input: Question: The presence of digestive tract with branched caeca extending to the posterior end of the adult worm is characteristic of the species: 
 Options:  <1> Hepatic fasciola. <2> Fasciolopsis buski. <3> Dicrocoelium dentriticum. <4> Paragonimus westermani. <5> Clonorchis sinensis.


Output: 1