You will be given a definition of a task first, then some input of the task.
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'.

Question: In a clinical trial that evaluates the efficacy of a hypolipidemic agent in the primary prevention of coronary heart disease, if the researchers have planned analysis of intermediate results and in view of them suspending the study before its completion they must know that:
Options: <1> The study can only be interrupted when in some intermediate analysis there is a difference between the results of the interventions, p <0.05. <2> Only interruption is justified in those studies that have mortality as the outcome variable. <3> If the intervention is safe, the study can not be interrupted before it has finished. <4> When a clinical trial is interrupted early, the effect of the evaluated intervention is often overestimated. <5> The performance of intermediate analyzes decreases the Type I error.
Output:
4