NZEC Runtime Error

inpt = raw_input()
withdraw, initial = [float(i) for i in inpt.split(' ')]

if float(withdraw) > 0 and float(initial) >=0:
        if float(initial) - float(withdraw)>0 and float(withdraw)%5==0: 
        final = float(withdraw) + 0.50
        print float(initial)-final
    else:
        print initial