Solved on an illustration not Tex.
Merge commit 'd8f356c0bf04597f5721964dfe49068a2b1ea573' into PR/ex1.19
Solved ex1.19 by using LaTeX
Fix LaTeX
Merge branch 'master' into PR/ex1.19
Fix LaTeX
Merge pull request #23 from naoiwata/PR/ex1.19

Solved 1.19
Merge commit '4d8c6e2861b0c787a127eff1aff5bf45267f04da' into PR/ex1.14
Modify tree structure