C study main
study
Revert "C study main"

This reverts commit 8e41ecf9a00935d34519a81f3c5d355698b9629a.
C
Revert "Revert "C study main""

This reverts commit 01e3b2031ba936b2b0a595789d4599f9e549e74c.
Revert "study"

This reverts commit 5f59d49c2fa24e05d8b03bc51fe9609bdf176dc0.
Revert "C study main"

This reverts commit 8e41ecf9a00935d34519a81f3c5d355698b9629a.