Revert "第1题：A+B+C问题"

This reverts commit 25de7843c6319a76d6d1d58d53a32345a3401f3d.
Revert "Revert "第1题：A+B+C问题""

This reverts commit befdd28469dc1244650b404ac2c5c01c998c2424.
Revert "Revert "Revert "第1题：A+B+C问题"""

This reverts commit d16a25bbe6af969bc4db27eb976e49348a2309f7.
Revert "Revert "Revert "Revert "第1题：A+B+C问题""""

This reverts commit d162890e0196cf2e39e1afc7e112375eceaba805.