'''
Exercise 2: Write a program to prompt for a file name, and then read through the file
and look for lines of the form:

X-DSPAM-Confidence:0.8475

When you encounter a line that starts with “X-DSPAM-Confidence:” pull apart the line
to extract the floating-point number on the line. Count these lines and then compute
the total of the spam confidence values from these lines. When you reach the end of
the file, print out the average spam confidence.

Enter the file name: mbox.txt
Average spam confidence: 0.894128046745
Enter the file name: mbox-short.txt
Average spam confidence: 0.750718518519
Test your file on the mbox.txt and mbox-short.txt files.

'''
arquivo = input('Enter the file name: ')
texto=open(arquivo)
listanum=list()
for linha in texto:
    if linha.startswith('X-DSPAM-Confidence:') == True:
        listanum.insert(1,float(linha[linha.find(': ')+1:]))
print('Average spam confidence:',sum(listanum)/len(listanum))
