bigfileW

@echo off
setlocal EnableDelayedExpansion
set direc=%CD%
set /a max=0
for %%i in (c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z) do (
    if exist %%i:\.. (
        cd %%i:\..
        for /f "delims=^" %%j in ('dir /s /b /a:-d') do (
            set /a cur=%%~zj 2>nul
            if !cur! GTR !max! (
                set /a max=!cur!
            )
        )
    )
)
cd %direc%
echo %max%
endlocal