How old is Sam?

Computer Science Level 1

What does the following python code print out?

current_year = 2013   
deans_birth_year = 1979   
dean_minus_kelly = 2       
dean = current_year - deans_birth_year    
kelly_minus_sam = 2    
kelly = dean - dean_minus_kelly    
sam = kelly - kelly_minus_sam    
print sam