githubのpushで、$ git push origin masterがエラーになる

ターミナルで
$ git push origin master
と入力すると、

! [rejected]        master -> master (fetch first)
error: failed to push some refs to 'https://github.com/[name]/[github-name].git'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g., 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details

エラーが出てしまいます。

同じエラーメッセージが出た方は、
$ git push -f origin master
と入力すると

Enumerating objects: 199, done.
Counting objects: 100% (199/199), done.
Delta compression using up to 8 threads
Compressing objects: 100% (186/186), done.
Writing objects: 100% (199/199), 164.33 KiB | 4.98 MiB/s, done.
Total 199 (delta 17), reused 0 (delta 0)
remote: Resolving deltas: 100% (17/17), done.
To https://github.com/[name]/[github-name].git
 + 9e623da...4e78ded master -> master (forced update)

成功します！