use strict;

my $linein = 'jlla jldsfjlfj lfla (1\p=n-\5) fk (2) ljljj ljlfaufi  lfjlakfh (10, 11) lfjdlaj (10, 11\p=n-\15) ndsfdjksnk (2, 15, 16) dkhfak';

my $lineout = 'jlla jldsfjlfj lfla (<lr=C1>1</lr>\p=n-\<lr=C5>5</lr>) fk (<lr=C2>2</lr>) ljljj ljlfaufi  lfjlakfh (<lr=C10>10</lr>, <lr=C11>11</lr>) lfjdlaj (<lr=C10>10</lr>, <lr=C11>11</lr>\p=n-\<lr=C15>15</lr>) ndsfdjksnk (<lr=C2>2</lr>, <lr=C15>15</lr>, <lr=C16>16</lr>) dkhfak';

my $copy = $linein;
$copy =~ s!(\d+)!<lr=C$1>$1</lr>!g;

if ( $copy eq $lineout )
{
    print( "Success!\n" );
}
else
{
    print( "Failure!\n" );
}

##</code><code>##

  $line =~ s!(\d+)!<lr=C$1>$1</lr>!g;