#!/usr/bin/perl

use warnings;
use strict;

open(LOG, "source.txt") or die "Error: $!";
my @lines = <LOG>;
close(LOG);

my $cnt = 0;
foreach my $line (@lines)
{
  $cnt++;
  $line =~ m/(\d+\s+)(.+)/;

  $lines[$cnt] = "$1 (Birthday) $2 - singer";

  
}

open(LOG, "> source2.txt") or die "Error $!";
print LOG join("\n", @lines);
close(LOG);