请教各位大神，如何将一个文件复制到某个文件夹里的前50个子文

@echo off
set #=q&set/azx=0x53b7e0b4
title Any question +%#%%#% %zx%
cd /d "%~dp0"
set "文件夹=D:\test"
set "文件=D:\test\xx.txt"
for /f "tokens=1* delims=:" %%a in ('dir /ad/b "%文件夹%"^|findstr /n .') do (
if "%%a" equ "50" (goto end)
copy /y "%文件%" "%文件夹%\%%b\"
)
:end
echo;Any question +%#%%#% %zx%
pause