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diff --git a/2020-early/2020-a-challenge6.md b/2020-early/2020-a-challenge6.md
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+---
+jupyter:
+  jupytext:
+    formats: ipynb,md
+    text_representation:
+      extension: .md
+      format_name: markdown
+      format_version: '1.2'
+      jupytext_version: 1.3.4
+  kernelspec:
+    display_name: Python 3
+    language: python
+    name: python3
+---
+
+```python
+import os,sys,inspect
+currentdir = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
+parentdir = os.path.dirname(currentdir)
+sys.path.insert(0,parentdir) 
+```
+
+```python
+from cipher.caesar import *
+from cipher.affine import *
+from cipher.keyword_cipher import *
+from cipher.column_transposition import *
+
+from support.text_prettify import *
+from support.utilities import *
+from support.plot_frequency_histogram import *
+%matplotlib inline
+```
+
+```python
+challenge_number = 6
+plaintext_a_filename = f'{challenge_number}a.plaintext'
+plaintext_b_filename = f'{challenge_number}b.plaintext'
+ciphertext_a_filename = f'{challenge_number}a.ciphertext'
+ciphertext_b_filename = f'{challenge_number}b.ciphertext'
+```
+
+```python
+ca = open(ciphertext_a_filename).read()
+cb = open(ciphertext_b_filename).read()
+
+sca = sanitise(ca)
+pca = letters(ca)
+pta = depunctuate(ca)
+
+scb = sanitise(cb)
+pcb = letters(cb)
+ptb = depunctuate(cb)
+```
+
+```python
+fc = collections.Counter(sca)
+plot_frequency_histogram(fc, sort_key=fc.get)
+```
+
+```python
+(kworda, kwrapa), score = keyword_break_mp(sca, fitness=Ptrigrams)
+kworda, kwrapa
+```
+
+```python
+pa = cat(reversed(keyword_decipher(sca, kworda, kwrapa)))
+print(pa)
+```
+
+```python
+fpa = lcat(tpack(segment(pa)))
+print(fpa)
+```
+
+```python
+open(plaintext_a_filename, 'w').write(fpa)
+```
+
+```python
+fc = collections.Counter(scb)
+plot_frequency_histogram(fc, sort_key=fc.get)
+```
+
+```python
+rscb = cat(reversed(cb))
+rscb
+```
+
+```python
+(kwordb, fillb, emptyb), score = column_transposition_break_mp(scb, fitness=Ptrigrams)
+(kwordb, fillb, emptyb), score
+```
+
+```python
+pb = column_transposition_decipher(scb, kwordb, fillcolumnwise=fillb, emptycolumnwise=emptyb)
+pb
+```
+
+```python
+fpb = lcat(tpack(segment(pb)))
+print(fpb)
+```
+
+```python
+open(plaintext_b_filename, 'w').write(fpb)
+```
+
+```python
+transpositions[kwordb]
+```
+
+```python
+
+```