Revert "Initial commit"

This reverts commit 96a896be11b94a319d07d1789bc835fbc88b748b.
Revert "Revert "Initial commit""

This reverts commit 0c967aaeac7e6ce4ecb83d992d86ccd9499aff12.
hw1

hand in hw1
hw1

....
Merge pull request #2 from lijj47/master

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