We have updated the execution environment for `C++23 (GCC 15.2.0)`. **【Background】** A compiler bug was reported in `C++23 (GCC 15.2.0)`. In general, we do not make additional changes after the final update of a language environment. However, since C++ is used by many AtCoder users and the potential impact may be significant, the contest admins have decided to make an exceptional update. **【Changes】** The following compile option has been removed: `-flto=auto` This option was included not only in the execution command, but also in the installation command for the environment. Therefore, we have reinstalled the `C++23 (GCC 15.2.0)` environment. The installation script is designed so that the same contents are installed regardless of when it is executed, so we do not expect this reinstallation to cause any differences. However, there may be minor differences in dependencies or other details. Please refer to the following page for the specific installation script: https://img.atcoder.jp/file/language-update/2025-10/language-list.html **【Application Time】** This change was applied around 18:00 on June 15, 2026 (JST). Submissions made after this change will use the updated execution environment. **【Scope of Impact】** This change applies only to `C++23 (GCC 15.2.0)`. Other languages and compiler versions are not affected. **【Rejudging】** We will not perform rejudging due to this change.