# https://www.calculator.net/gcf-calculator.html
# https://stackoverflow.com/questions/32480392/making-a-gcf-calculator-in-python
import fractions
def GCF(arr):
    a = arr[0]
    b = arr[1]
    
    work = fractions.gcd
    return work(a,b)




print(GCF([12, 28]))
            
            
            
  
  
            
        

        
        

