\usepackage[a4paper, hmargin=1in, vmargin=1in]{geometry}
\usepackage[a-2u]{pdfx}
+\usepackage{iftex}
+\ifpdftex
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
-\usepackage{lmodern}
\usepackage{textcomp}
+\fi
+\usepackage{lmodern}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{amsfonts}