new file: chapter4.txt
new file: chapter5.md
new file: chapter4.md
Deleted chapter4.txt
new file: chapter6.md
new file: chapter7.md
new file: chapter8.md
new file: chapter9.md
new file: chapter10.md
Created chapter10.md
new file: chapter11.md
new file: chapter12.md
new file: chapter13.md
Created chapter13.md
new file: chapter14.md
new file: chapter15.md
new file: chapter16.md
new file: chapter17.md
new file: chapter18.md
new file: chapter19.md