use strict;
use warnings;

$/ = "\n\n";

while ( <DATA> ) {
    if( my( $number ) = m/(\d+)/ ) {
        s/\b\p{Alpha}+\b/$number/g;
    } else {
        warn "Malformed record in input line $.\n$_\nContinuing.\n";
    }
    print;
}


__DATA__
0       ASDF
        ASEE
        ASEE

13      DERG
        DREG

28      QWER
        QWER

42      WERT
        WERT
        WERT

55      QWEASD
        QWEASD
        QWEASD
        QWEASD

##</code><code>##

0       0
        0
        0

13      13
        13

28      28
        28

42      42
        42
        42

55      55
        55
        55
        55