sam/python

def frac_add():
    fraction_1=input('Please enter a fraction:\n')
    fraction_1="".join(fraction_1.split())
    fraction_1=fraction_1.replace('/',' ')
    fraction_1=fraction_1.split()
    fraction_2=input('Please enter another fraction:\n')
    fraction_2="".join(fraction_2.split())
    fraction_2=fraction_2.replace('/',' ')
    fraction_2=fraction_2.split()
    letters = set('abcdefghijklmnopqrstuvqxyz')
    print(fraction_1)
    print(fraction_2)
    if letters in set(fraction_1):
        print(str(fraction_1).strip("['']"), 'is not a valid fraction. Ending program.')
    elif letters in set(fraction_2):
        print(str(fraction_2).strip("['']"), 'is not a valid fraction. Ending program.')
    elif fraction_1[1]==fraction_2[1]:
        same_denominator=(int(fraction_1[0])+int(fraction_2[0]))
        same_denominator=str(same_denominator)
        print(fraction_1[0]+"/"+fraction_1[1]+" + "+fraction_2[0]+"/"+fraction_2[1]+" = "+same_denominator+"/"+fraction_1[1])
    elif fraction_1[1]!=fraction_2[1]:
        numerator=((int(fraction_1[0])*int(fraction_2[1]))+(int(fraction_2[0])*int(fraction_1[1])))
        numerator=str(numerator)
        denominator=int(fraction_2[1])*int(fraction_1[1])
        denominator=str(denominator)
        print(fraction_1[0]+"/"+fraction_1[1]+" + "+fraction_2[0]+"/"+fraction_2[1]+" = "+numerator+"/"+denominator)

try:
    frac_add()
except NameError,e:
    print 'bad input'