poter

@echo off
setlocal enableDelayedExpansion
for /f "tokens=*" %%i in ('dir /b /a-d') do (
if not "%%i"=="%~nx0" set a=%%i
for /f %%a in ("!a!") do (
set b=%%a&call set "b=%%b:!b:~0,4!=%%"
ren %%i !b!>1
)
)