Solved ex1.15
Modify
Merge pull request #30 from naoiwata/PR/ex1.15

Solved ex1.15
fix .gitignore conflict
Merge pull request #38 from iriya-ufo/fix_conflict

fix .gitignore conflict
Solved 1.13
Merge pull request #39 from iriya-ufo/ex1.13

LGTM:)
Fix LaTeX