You get ten copies of *Sentimental Education: The Story of a Young Man* with a certain difference between them.
![https://github.com/n00bSec/n00bSec.github.io/raw/master/pics/DefCamp/DefCampCTFStoryOfAYoungMan.png](http://)
The flag is in each of these differences. I didn't want to reinvent the wheel, since Python's so good already for analyzing texts,so I at least did enough Googling to find out about difflib. I then spent a little time hacking together soln.py...```#!/usr/bin/python
import difflibfrom subprocess import Popen, PIPE
files = [(str(i).rjust(4, '0') + '.txt') for i in range(1,11)]output_lines = []
for f1 in range(len(files)-1):  f2 = f1+1  p = Popen(['diff', files[f1], files[f1+1]], stdout=PIPE)  lines = p.stdout.readlines()[1::2]  for line in lines:    output_lines.append(line)
guess = ''#Each of these sections look breakable into foursfor i in range(0,len(output_lines),2):  print str(i) + "..."  original = output_lines[i][2:]  replaced = output_lines[i+1][2:]  print original  print replaced  diff = ''  for x in difflib.ndiff(original[2:],replaced[2:]):    if x.startswith('+'):      diff += x[2:]  print diff.replace(' ','')  guess += diff.replace(' ','')
print "This your flag?: " + guess # DCTF{7ba610cc5da3966b7c64a81c3cfcdb1b1d09e3de5ad1189268bf0e618ff71f08}'```