Hello. I’m trying to enter this text in Texmaker, to convert via PDFlateEX to the PDF file, but in the end I get an empty sheet.
What to do?

\ documentclass [12pt] {article}
% This string is a comment, it will not be shown in the output file.
\ UsePackage {UCS}
\ UsePackage [UTF8X] {inputenc}% turn on utf8 support
\ UsePackage [RUSSIAN] {Babel}% turn on the package to support the Russian language
\ Title {\ Latex}
\ Date {}
\ Author {}
\ Begin {Document}
 \ maketitle
 \ Latex {} "--- This is a kind of text preprocessor for \ tex {}"
 Computer layout programs. \ Latex {} is programmable and
 extensible, which allows you to automate most of the aspects
 set, including numbering, cross-links, tables and images
 (their placement and signature to them), general view of the page, bibliography and
 Much more. \ Latex {} was originally written Lassley Lamport
 In 1984 and became the most popular way of use \ Tex {} A;
 Very few people are written today on the original \ Tex {} e. Current
 Version is \ Latexe.
 \ Newline
 \ begin {eqnarray}
  E & amp; = & amp; MC ^ 2 \\
  m & amp; = & amp; \ FRAC {M_0} {\ sqrt {1- \ FRAC {V ^ 2} {C ^ 2}}}
 \ end {eqnarray}
  \ End {Document}

Answer 1

And what errors gives?

Try replace

\ usepackage {ucs}
\ UsePackage [UTF8X] {inputenc}% turn on utf8 support

on

\ usepackage [utf8] {inputenc}% turn on support utf8

Miktex 2.9 correctly displays.

Answer 2, Authority 200%

Most likely this problem has long been solved, but just in case – insert the line

\ UsePackage [T2A] {fontenc}

after

\ UsePackage [UTF8] {inputenc}

Amendment: This line is no longer required – it is enough to change UTF8 on utf8x. Moreover, if you are inserted t2a, then as indicated in the comments below (dmitry nosachev ), this inset will lead to the fact that the Russian text copied from the PDF file turns out to be encoded in something like KOI-8 Instead of standard Windows encoding.

Answer 3

For some reason, I have a PDF from PDFlateEX since some moment started to give the damask beam when copying text. Texlive under Windows. I corrected the preamble, removing the T2A, and everything became good:

\ UsePackage [UTF8X] {inputenc}
\ UsePackage [English, Russian] {Babel}
\ UsePackage {CMAP}