\usepackage{calc}
\usepackage{geometry}
\geometry{paper=a4paper, noheadfoot, margin=0pt}
% parameters required to trim `left' and `right' watermarks for A4 case.
\newcommand{\leftTrimleft}{50bp}
\newcommand{\leftTrimright}{110bp}
\newcommand{\leftTrimtop}{0bp}

\newcommand{\rightTrimleft}{50bp}
\newcommand{\rightTrimright}{110bp}
\newcommand{\rightTrimtop}{0bp}