documentclass[12pt,a4paper]{report}
usepackage[utf8]{inputenc}
usepackage[farsi]{babel}
author{S. M. Saadatmand}
begin{document}
    سلام
end{document}

line 133: Encoding scheme `LAE' unknown. ...ntencoding{LAE}fiselectfontalefhamza}}
line 133: Command alefhamza unavailable in encoding OT1. ...ntencoding{LAE}fiselectfontalefhamza}}
line 135: Encoding scheme `LAE' unknown. ... fontencoding{LAE}fiselectfontHaa}}
line 135: Command Haa unavailable in encoding OT1. ... fontencoding{LAE}fiselectfontHaa}}
line 137: Encoding scheme `LAE' unknown. ... fontencoding{LAE}fiselectfontdamma}}
line 137: Command damma unavailable in encoding OT1. ... fontencoding{LAE}fiselectfontdamma}}
line 139: Encoding scheme `LAE' unknown. ... fontencoding{LAE}fiselectfontkasra}}
line 139: Command kasra unavailable in encoding OT1. ... fontencoding{LAE}fiselectfontkasra}}
line 6: Package inputenc Error: Unicode character س (U+0633)(inputenc) not set up for use with LaTeX. س
line 6: Package inputenc Error: Unicode character ل (U+0644)(inputenc) not set up for use with LaTeX. سل
line 6: Package inputenc Error: Unicode character ا (U+0627)(inputenc) not set up for use with LaTeX. سلا
line 6: Package inputenc Error: Unicode character م (U+0645)(inputenc) not set up for use with LaTeX. سلام