You will be given a definition of a task first, then some input of the task.
Given a list of steps and an additional step, determine where the step fits into the original list of steps. A correct answer, correctly places the given step into the set of steps so that it creates a new plausible set of steps. Output must be formatted as 'After step n', where n is the step number after which the given additional step is to be inserted.

Steps: (1) The oxygen travels to the lungs through the windpipe (2) The air sacs in the lungs send the oxygen into the blood stream (3) The carbon dioxide in the blood stream is transferred to the air sacs (4) The lungs expel through the nose or mouth back into the environment.  
Where does the following step fit into the given list of steps: You breathe oxygen into your body through the nose or mouth 
Output:
 Before step 1. 