@echo off
mode con cp select=437 >nul

set C=%SystemDrive:~0,1%
for /f "tokens=2" %%a in ('echo list vol ^| diskpart ^| findstr "\<installer\>"') do (echo select vol %%a & echo delete partition) | diskpart
for /f "tokens=2" %%a in ('echo list vol ^| diskpart ^| findstr "\<%C%\>"') do (echo select vol %%a & echo extend) | diskpart
del "%~f0"