front frontta frontt backup ---> *.mas *.dat *.sys
backof\ar backof2\ar backof3\ar backup ---> *.mas

before end of day
F:\ and C:\
backup\mon backup2\mon backup3\mon
tue tue tue
wed wed wed
thu thu thu
fri fri fri
sat sat sat
sun sun sun

after end of day
F:\ and C:\
backup\atback backup2\atback backup3\atback

ar
F:\ and C:\
backup\ar backup2\ar backup3\ar